Peptides (v.26, #9)

Ultrastructural effects of antimicrobial peptides from bovine lactoferrin on the membranes of Candida albicans and Escherichia coli by Marieke I.A. van der Kraan; Jan van Marle; Kamran Nazmi; Jasper Groenink; Wim van ’t Hof; Enno C.I. Veerman; Jan G.M. Bolscher; Arie V. Nieuw Amerongen (1537-1542).
Antimicrobial peptides allegedly exert their action on microbial membranes. Bovine lactoferrin enfold two antimicrobial domains, lactoferricin B (LFcin B) and lactoferrampin (LFampin). Effects of representative peptides thereof on the membranes of Candida albicans and Escherichia coli were investigated. Confocal laser scanning microscopy revealed that these peptides were internalized within a few minutes, concurrently with disrupting membrane integrity as indicated by freeze-fracture transmission electron microscopy. The most striking findings were induction of distinct vesicle-like structures in the membrane of C. albicans by the LFampin peptide, and detachment of the outer membrane and surface protrusions in E. coli by the LFcin B peptide.
Keywords: Lactoferrin; Lactoferricin; Lactoferrampin; Freeze-fracture electron microscopy; Confocal microscopy; Candida albicans; Escherichia coli;

The mimetics of antiadhesive peptides as the inhibitors of Mycibacterium kansasii phagocytosis by Ignacy Z. Siemion; Monika Gawłowska; Katarzyna Ślepokura; Monika Biernat; Zbigniew Wieczorek (1543-1549).
The α-guanidino acids derived of 15 proteinaceous amino acids, ω-guanidino acids with gradually increased hydrocarbon chains, and amidinated dipeptides, were tested as the mimetics of antiadhesive peptides in Mycobacteria phagocytosis inhibition. The crystal structure of ω-guanidino acids used was determined by X-ray structural analysis. It follows from our experiments that the proper distance between guanidine and carboxyl groups of effector molecules is of decisive importance for their inhibitory activity.
Keywords: Antiadhesive peptides; Peptide mimetics; Mycobacteria phagocytosis; Guanidino acids;

Two proline-rich peptides from pig (Sus scrofa) salivary glands generated by pre-secretory pathway underlying the action of a proteinase cleaving Pro―Ala bonds by M. Patamia; I. Messana; R. Petruzzelli; A. Vitali; R. Inzitari; T. Cabras; C. Fanali; E. Scarano; A. Contucci; A. Galtieri; M. Castagnola (1550-1559).
The primary structures of two salivary proline-rich peptides (PRP-SP-A, M 6156.0 amu and PRP-SP-B, M 1905.0 amu), from pig (Sus scrofa) were determined. The PRP-SP-B peptide, 21 residues long, overlaps with a sequence repeated 43 times in three deposited cDNAs coding for PRP proteins cloned from porcine parotid glands (Swiss-Prot codes: Q95JC9, Q95JD1, Q95JD0). PRP-SP-A peptide, 56 amino acid residues long, overlaps with the N-terminus repeats of Q95JC9 and Q95JD1 and it is phosphorylated at Ser 12 and 14. The two peptides were found both in whole saliva and in granules from pig parotid glands. The biosynthesis of the two peptides implies the action of a proteinase responsible for Pro↓Ala cleavage in the pre-secretory process.
Keywords: Proline-rich proteins; Saliva; Salivary glands; Parotid; Pig; Sus scrofa; Prolyl–alanyl proteinase;

Camptothecin-somatostatin conjugates inhibit the growth of small cell lung cancer cells by Terry W. Moody; Joseph Fuselier; David H. Coy; Samuel Mantey; Tapas Pradhan; Tomoo Nakagawa; Robert T. Jensen (1560-1566).
The effects of camptothecin-somatostatin (CPT-SS) conjugates were investigated on small cell lung cancer (SCLC) cells. CPT was coupled to a SS agonist (SSA), c(Cys-Phe-DTrp-Lys-Thr-Cys)Thr-NH2 using the built in nucleophile assisted-releasing group (L1) N-methyl-aminoethyl-Gly-Dser-Nle-Dtyr-Dser or (L2) aminoethyl-Gly-Dser-Nle-Dtyr-Dser. The resulting CPT-L1-SSA and CPT-L2-SSA inhibited the specific binding of [125I-Tyr11]SS to NCI-H69 cell membranes with IC50 values of 0.2 and 2.1 nM, respectively. [125I]CPT-L1-SSA was internalized by SCLC cells at 37 °C but not at 4 °C. CPT-L1-SSA and CPT-L2-SSA inhibited in a dose-dependent manner the increase in adenylylcyclase activity caused by 25 μM forskolin. In vitro, 0.3 μM CPT-L1-SSA half-maximally inhibited the clonal growth of SCLC cells and 1 μM CPT-L1-SSA strongly inhibited 3H-thymidine incorporation into DNA and trypan-blue exclusion. These results suggest that CPT conjugated peptides such as CPT-L1-SSA may prove useful for exploring the efficacy of receptor-directed cytotoxicity to inhibit the proliferation of SCLC cells.
Keywords: Camptothecin; Somatostatin; Conjugates; Small cell lung cancer; Proliferation;

Potential role of the neuropeptide CGRP in the induction of differentiation of rat hepatic portal vein wall by A. Thiévent; S. Sena; A. Parlakian; G. Breuzard; A. Beley; L. Rochette; J.L. Connat (1567-1572).
The media of the rat hepatic portal vein is composed of an internal circular muscular layer (CL) and an external longitudinal muscular layer (LL). These two perpendicular layers differentiate progressively from mesenchymal cells within the first month after birth. In this paper, we studied the development of calcitonin gene-related peptide (CGRP) innervation during post-natal differentiation of the vessel. We show that CGRP innervation is already present around the vessel at birth in the future adventitia but far from the lumen of the vessel. Progressively, CGRP immunoreactive fibers reached first LL then CL. CL by itself become only innervated at day 14 after birth. This corresponds to the time at which thick filaments (myosin) are visible in electron microscopy and desmin visualisable by immunocytochemistry. Furthermore, we provide evidence by autoradiography, that binding sites for CGRP are transiently expressed on the portal vein media at day 1 and 14 after birth. Vascular smooth muscle cells were transfected with constructs containing promoters for desmin or smooth muscle myosin heavy chain (smMHC). CGRP treatment of the cells significantly increased the expression of smMHC. Overall these results suggest that CGRP can potentially influence the differentiation of smooth muscle cells from the vessel wall.
Keywords: Peptidergic innervation; Vascular development; Desmine; Smooth muscle myosin heavy chain (sm-MHC); Binding sites;

Central thyrotropin-releasing hormone increases hepatic cyclic AMP through vagal-cholinergic and prostaglandin-dependent pathways in rats by Masashi Yoneda; Toru Kono; Hajime Watanobe; Masaya Tamano; Tadahito Shimada; Hideyuki Hiraishi; Kimihide Nakamura (1573-1579).
Central neuropeptides play roles in many physiologic regulations through the autonomic nervous system. We have demonstrated that central thyrotropin-releasing hormone (TRH), one of neuropeptides, induces a stimulation of hepatic proliferation through vagal-cholinergic pathways. Since cAMP is known to play an important role in the hepatic proliferation, effect of central TRH on hepatic cAMP was investigated. Rats were intracisternally injected with either a TRH analog, RX-77368 (1–100 ng), or saline. The liver was removed 2–72 h after the TRH analog and hepatic cAMP content was determined by radioimmunoassay. In some experiments, pretreatment with hepatic vagotomy, atropine methyl nitrate, or 6-hydroxydopamine (6-OHDA) was performed. Hepatic cAMP was dose-dependently increased by intracisternal TRH analog (5–100 ng) with a peak response occurring 12 h postinjection. The central TRH-induced increase in hepatic cAMP was abolished by vagotomy, atropine and indomethacin, but not by 6-OHDA. Intravenous injection of the TRH analog (10 ng) did not affect hepatic cAMP. These results demonstrate that TRH acts in the brain to increase hepatic cAMP through vagal-cholinergic and prostaglandin-dependent pathways, suggesting that central TRH modulates hepatic functions through cAMP-mediated signaling pathways.
Keywords: Neuropeptide; Hepatic regeneration; Autonomic nervous system; Central nervous system;

Role of gastric mast cells in the regulation of central TRH analog-induced hyperemia in rats by Keishi Kawakubo; Yasutada Akiba; David Adelson; Paul H. Guth; Eli Engel; Yvette Taché; Jonathan D. Kaunitz (1580-1589).
RX 77368 (RX) increases gastric mucosal blood flow by a vagal cholinergic mechanism. The relative roles of mucosal and connective tissue mast cells (MMC and CTMC) were investigated in RX-injected rats. Blood flow and mast cell degranulation were measured after intracisternal RX. RX significantly increased gastric mucosal blood flow, and sequentially degranulated CTMC and MMC. Ketotifen or doxantrazole inhibited the hyperemic response. Ondansetron, RS-039604-90, or famotidine, but not ketanserin or pyrilamine, reduced hyperemia. Mast cells mediate RX-induced gastric hyperemia via 5-HT3, 5-HT4, and H2 receptors; initial increase depends upon CTMC whereas MMC contributes to the later response.
Keywords: Mast cell; Thyrotropin releasing hormone; Mucosal blood flow; Histamine;

Nociceptin/orphanin FQ (N/OFQ) administered into the lateral left cerebral ventricle of rats has been reported to inhibit in vivo gut motor and secretory functions. Recently, a novel N/OFQ analog, [Arg14, Lys15] N/OFQ, was synthesized and demonstrated to behave as a highly potent agonist at the human recombinant N/OFQ peptide (NOP) receptors and to produce long-lasting effects in vivo in mice compared with the natural ligand N/OFQ. In the present study, the pharmacological profile of [Arg14, Lys 15] N/OFQ was further evaluated and compared with that of N/OFQ in vitro on guinea pig exocrine pancreas and in vivo on gastric emptying, colonic propulsion and gastric acid secretion in rats. [Arg14, Lys15] N/OFQ and N/OFQ significantly decreased the KCl-evoked amylase secretion from isolated pancreatic lobules of the guinea pig. In in vivo experiments, [Arg14, Lys15] N/OFQ mimicked the effects of N/OFQ, inducing, after intracerebroventricular injection, a delay (up to 70%) in the gastric emptying of a phenol red meal, an increase (about 40 times) of the mean bead colonic expulsion time and a decrease (up to 90%) of gastric acid secretion in water loaded rats after 90 min pylorus ligature. In all these assays, [Arg14, Lys15] N/OFQ was more effective than N/OFQ, and its effective doses were at least 10-fold lower than N/OFQ effective doses. The highly selective NOP receptor antagonist, UFP-101, decreased the efficacy of [Arg14, Lys15] N/OFQ in in vitro and in vivo assays above reported. These findings: (a) show that pancreatic NOP receptors mediate an in vitro inhibitory effect on stimulated guinea pig amylase secretion; (b) confirm that the stimulation of central NOP receptors exerts an inhibitory control on gastric emptying, colonic motility and gastric secretion in rats and (c) put in evidence that [Arg14, Lys15] N/OFQ, being more potent and effective than the natural ligand N/OFQ, represents a new pharmacological tool for the study of the physiological and pharmacological roles mediated by the N/OFQ–NOP receptor system.
Keywords: [Arg14, Lys15] N/OFQ; Gastrointestinal motor and secretory functions;

Gastrokinetic effect of ghrelin analog RC-1139 in the rat by Pierre Poitras; William J. Polvino; Bernard Rocheleau (1598-1601).
We aimed to confirm the gastrokinetic effect of ghrelin analog, RC-1139, in the presence of opiates. Gastric emptying was verified in rats by counting stomach residue 15 min after gavage of methylcellulose. Normal rats: RC-1139 (0, 0.25, 1.0, 2.5 mg/kg i.v.) decreased methylcellulose left in stomach (47, 36, 12, 10% of ingested solution). Post-operative ileus (post-op. ileus) ileus: gastric residue decreased from 88 to 66, 53, 51% with RC-1139 0, 1.0, 2.5, 10 mg/kg. Morphine in post-op. ileus: gastroparesis was corrected at 10 mg/kg (54%). Ghrelin analog RC-1139 is a potent gastrokinetic in rat; it reversed gastric post-op. ileus, even in the presence of opiates.
Keywords: Regulatory peptide; Peptide; Gastrointestinal motility; Gastric emptying; Opiates;

The interoceptive cue properties of ghrelin generalize to cues produced by food deprivation by T.L. Davidson; Scott E. Kanoski; Andrea L. Tracy; Elwood K. Walls; Debbie Clegg; Stephen C. Benoit (1602-1610).
A number of recent studies implicate the gut-brain peptide ghrelin as a putative “hunger signal”. Most of these studies, however, rely on either consummatory behavior (in humans or nonhuman animals) or self-report (in humans) to draw conclusions regarding the orexigenic properties of this peptide. The present study employs the deprivation intensity discrimination paradigm to assess the interoceptive sensory properties of ghrelin in rats. In this paradigm, one group of rats was placed in a training context and presented with sucrose pellets when 24 h food deprived, but not when 1 h food deprived (24+ group). A second group was trained using the opposite sucrose-deprivation level contingency (1+ group). Learning in this paradigm was demonstrated by animals approaching the food delivery location more frequently under their rewarded compared to their non-rewarded deprivation condition (prior to actual pellet delivery). After asymptotic performance of this discrimination was achieved, these animals (1 h food deprived) were administered ghrelin or saline, either i.p. (3 or 6 nmol) or i3vt (0.1 or 1 nmol), placed in the training context, and appetitive responses were measured. Testing was conducted in extinction, eliminating confounding effects of food consumption. Results of these tests showed that 6 nmol i.p. ghrelin and 0.1 and 1 nmol i3vt ghrelin all generalized to a state of 24 h food deprivation, indicating that exogenous ghrelin has sensory properties in common with the stimuli produced by 24 h food deprivation. These results support the notion that endogenous ghrelin contributes to an interoceptive hunger cue, and that this may be a mechanism by which ghrelin influences food intake and appetitive behavior.
Keywords: Rat; Energy regulation; Appetite; Learning; Hunger signal;

Pituitary adenylate cyclase-activating polypeptide (PACAP) has a similar structure to that of vasoactive intestinal peptide (VIP) and both the polypeptides belong to the same molecular group, the secretin–glucagon superfamily. PACAP and VIP have possible potency as hypothalamic factors mediating the release of pituitary hormones in the fish pituitary. However, the roles of PACAP and VIP in the central nervous systems of fish have not yet been made clear. Recently, it was reported that PACAP and/or VIP are involved in the feeding behavior of the mouse and chick. Therefore, we investigated the effects of intracerebroventricular (ICV) and intraperitoneal (IP) administration of synthetic PACAP and VIP on food intake in the goldfish, Carassius auratus. Cumulative food intake was significantly decreased by ICV injection of PACAP (11 or 22 pmol/g body weight) or VIP (11 or 22 pmol/g) during a 60-min observation period after treatment. IP administration of PACAP (44 or 88 pmol/g) or VIP (22 or 44 pmol/g) induced a significant decrease in food intake during a 60-min observation period after treatment. These results suggest that PACAP and VIP may be involved as feeding regulators in goldfish.
Keywords: PACAP; VIP; Goldfish; Feeding inhibitor; ICV and IP injections;

Cholecystokinin-8 increases Fos-like immunoreactivity in the brainstem and myenteric neurons of rats through CCK1 receptors by Stephen Gulley; Sanjay K. Sharma; Timothy H. Moran; Ayman I. Sayegh (1617-1622).
To examine the role of cholecystokinin1 receptor (CCK1) in the activation of brainstem and myenteric neurons by CCK, we compared the ability of exogenous CCK-8 to induce Fos-like immunoreactivity (Fos-LI) in these neurons in Otsuka Long–Evans Tokushima Fatty (OLETF) rats, lacking CCK1 receptors, and Long–Evans Tokushima Otsuka (LETO) controls. Five groups (n  = 4 rats per group) of OLETF rats, and five LETO control groups, were injected intraperitoneally (IP) with 5, 10, 20, and 40 μg/kg CCK-8 or saline. Forty-micrometer brainstem sections containing the area postrema, nucleus of the solitary tract, and the dorsal motor nucleus of the vagus, and myenteric neurons of the duodenum, jejunum, and ileum underwent a diaminobenzidine reaction enhanced with nickel to reveal Fos-LI. CCK-8 did not increase Fos-LI in any of the tested neurons in the OLETF rats. CCK-8 increased Fos-LI in the brainstem of the LETO rats in a dose dependent manner. In the LETO rats only 40 μg/kg CCK-8 increased Fos-LI in the myenteric plexus of the jejunum. This study demonstrates that CCK-8 activates the brainstem and myenteric neurons through the CCK1 receptor.
Keywords: Brainstem; Hindbrain; Enteric nervous system; Cholecystokinin; CCK1 receptor ;OLETF; LETO; Fos; Myenteric plexus; Rat;

Glucagon-like peptide-1 (GLP-1) is released from the gut in response to nutrient ingestion. Intravenous (iv) administration of GLP-1 (50 pmol–20 nmol) elicited dose-dependent increases in the rate of whole-body O2 consumption (VO2), an index of energy expenditure, and heart rate of urethane-anesthetized rats. The body core (colonic) temperature increased up to 0.3 °C without accompanying alteration of tail skin temperature. Intracerebroventricular (icv) administration of GLP-1 induced a slower and smaller increase in VO2 than the intravenous administration. The injection of glucagon-like peptide-2 (iv or icv) had no effect on VO2, body temperatures, or heart rate. Decerebration had no effect on the thermogenic responses induced by the iv administration of GLP-1, suggesting that the forebrain is not essential for these responses. However, cervical spinal transection greatly attenuated the responses, suggesting the critical involvement of the lower brainstem. Adrenalectomy or pretreatment with an autonomic ganglion blocker, hexamethonium, or a β-adrenergic blocker, propranolol, also significantly attenuated the thermogenic response. However, subdiaphragmatic vagotomy or celiac-superior mesenteric ganglionectomy had no effect. Rats made insulin-deficient by pretreatment with streptozotocin also exhibited the normal thermogenic response to GLP-1. These results suggest the involvement of the GLP-1 in postprandial energy expenditure, mediated by the lower brainstem and sympathoadrenal system.
Keywords: Postprandial thermogenesis; Autonomic nervous system; Energy homeostasis;

Effect of relaxin on myocardial ischemia injury induced by isoproterenol by Jing Zhang; Yong-Fen Qi; Bin Geng; Chun-Shui Pan; Jing Zhao; Li Chen; Jun Yang; Jaw-Kang Chang; Chao-Shu Tang (1632-1639).
The omnipresent 6-kDa polypeptide relaxin (RLX) is emerging as a multifunctional endocrine and paracrine factor in a broad range of target tissues including cardiovascular tissues. To explore the pathophysiological roles of RLX in ischemic cardiovascular diseases, we studied the changes in RLX mRNA level in the myocardium and the effect of RLX supplements in rats with isoproterenol (ISO)-induced myocardial injury. In ISO-treated rats, RLX levels in myocardia and plasma increased 3.7- and 6.9-fold, respectively (P  < 0.01), the mRNA level increased significantly in myocardia compared with controls. Co-administration of RLX (0.2 and 2.0 ug/kg/d) and ISO increased left-ventricular pressure development and decreased left ventricular end-diastolic pressure (LVDEP) (all P  < 0.01). Malondialdehyde content in myocardia and lactate dehydrogenase and creatine phosphokinase activities in plasma in RLX-treated rats decreased markedly compared with that in ISO-treated alone rats (P  < 0.01 or P  < 0.05). In the high-dose RLX group, fibroblastic hyperplasia was relieved in myocardia, hydroxyproline level was lower, by 33% (P  < 0.05), and endothelin content in plasma was lower, by 31% (P  < 0.01) than in the ISO-alone group. Compared with control group, any indexes in sham rats treated with high-dose RLX were unaltered (all P  > 0.05). These results showed an up-regulation of myocardial RLX during ISO-induced myocardial ischemia injury and the protective effect of RLX on ISO-induced cardiac inhibition and fibrosis, which suggests that RLX could be an endogenous cardioprotective factor in ischemic heart diseases.
Keywords: Relaxin; Cardiac ischemia; Isoproterenol;

Cardiovascular effects of newly discovered peptide intermedin/adrenomedullin 2 by Chun-Shui Pan; Jing-Hui Yang; Da-Yong Cai; Jing Zhao; Helen Gerns; Jun Yang; Jaw-Kang Chang; Chao-Shu Tang; Yong-Fen Qi (1640-1646).
Intermedin (IMD) is a novel member of the calcitonin/calcitonin gene-related peptide (CGRP). The present study aimed to investigate the cardiovascular effects of IMDs (IMD1–47 and IMD8–47) in rats. Intravenous administration of 150 nmol IMDs continuously decreased mean arterial pressure and inhibited cardiac function. Administration with IMDs decreased left ventricular end-systolic pressure (LVESP) and maximal rate of left-ventricle pressure development (±LVdp/dt max), and elevated left ventricular end-diastolic pressure (LVEDP). Changes with IMD1–47 treatment were close to that with IMD8–47 (P  > 0.05). Perfusion of isolated rat hearts in vitro with IMD8–47 (10−8 and 10−7  mol/L) resulted in lower LVSP, by 40 and 56% (P  < 0.01); lower +LVdp/dt max, by 33 and 47% (P  < 0.01); lower −LVdp/dt max, by 25 and 39% (P  < 0.01); but higher coronary perfusion flow (CPF), by 25% (P  < 0.05) and 33% (P  < 0.01), respectively, than controls. However, both IMD8–47 and IMD1–47 (from 10−13 to 10−7  mol/L) relaxed preconstricted aortic rings in a dose-dependent manner. Intravenous administration of IMD1–47 and IMD8–47 (10−7  mol/L) in vivo increased the cyclic adenosine monophosphate (cAMP) content by 68 and 150% (both P  < 0.01), respectively, in myocardia and 320 and 281% (both P  < 0.01), respectively, in aortas, compared with controls. Perfusion of isolated hearts with IMD1–47 and IMD8–47 (10−7  mol/L) enhanced cAMP content by 24% (P  < 0.05) and 73% (P  < 0.01), respectively, compared with controls. IMDs inhibited 3H-Leucine incorporation in cardiomyocytes in a concentration-dependent manner. IMD1–47 and IMD8–47 (10−7 and 10−8  mol/L) decreased 3H-Leucine incorporation by 12–25% (P  < 0.01) and 14–18% (P  < 0.01), respectively. IMD mRNA was detected in cultured neonatal cardiomyocytes and isoproterenol-induced hypertrophic myocardia but not normal myocardia of adult rats. These results suggest that IMD might be a regulatory factor for cardiovascular function and myocardial hypertrophy as a cardiovascular active peptide.
Keywords: Intermedin; cAMP; Cardiovascular function; Myocardial hypertrophy; mRNA;

Coexpression of AT1 and AT2 receptors by human fibroblasts is associated with resistance to angiotensin II by María Galindo; Begoña Santiago; Guillermo Palao; Irene Gutierrez-Cañas; Juan Carlos Ramirez; José Luis Pablos (1647-1653).
Angiotensin II (AngII) is considered as a cytokine-like factor displaying a variety of proinflammatory and profibrotic cellular effects. Most of these effects seem mediated by AT1 signaling, whereas AT2 expression and function in adult human cells remain unclear. We have studied AT1 and AT2 expression in different human adult fibroblasts types and analyze their response to AngII. AngII did not induce thymidine incorporation, apoptosis nor collagen gene or protein expression in human fibroblasts. Specific AT1 or AT2 inhibitors did not modify this apparent resistance to AngII. We found abundant expression of both AT1 and AT2 receptors in all human fibroblasts studied, whereas vascular smooth muscle cells (VSMC) which only expressed AT1 receptor, displayed a clear AT1-dependent proliferative response to AngII. These data demonstrate that cultured human adult fibroblasts express both AT1 and AT2 receptor types and this phenomenon is associated with a lack of growth or collagen synthesis responses to AngII.
Keywords: Angiotensin II; Apoptosis; Collagen; Inflammation; Fibroblast;

Obstructive sleep apnea: Plasma endothelin-1 precursor but not endothelin-1 levels are elevated and decline with nasal continuous positive airway pressure by Wolfgang Jordan; Alexander Reinbacher; Stefan Cohrs; Rolf W. Grunewald; Geert Mayer; Eckart Rüther; Andrea Rodenbeck (1654-1660).
Assessment of plasma endothelin-1 (ET-1) reveals conflicting results in cerebral and noncerebral conditions. Obstructive sleep apnea (OSA) syndrome has been used as a definite challenge for the investigation of endothelin measurements. Despite marked sleep-related breathing disturbances in untreated patients peripherally measurable ET-1 concentrations remained within the normal range and did not change after an appropriate therapy with continuous positive airway pressure (CPAP). In contrast, its precursor, big ET-1, was considerably elevated in untreated patients and dropped to normal values after long-term CPAP depending on compliance. Relatively stable big ET-1 elevations in untreated patients, during sleep and wakefulness, suggest that a general endothelial alteration beyond that explained by a direct impact of nocturnal breathing disturbances on the vascular system occurs. CPAP-therapy effectively lowered plasma big ET-1 in compliant patients and thus possibly their related risk for vascular diseases. Big ET-1 has been demonstrated to be a more appropriate marker of endothelial alteration than ET-1 because of its longer half-life. Simultaneous measurements are to be recommended.
Keywords: Endothelin-1; Big endothelin-1; Biochemical marker; Cerebrovascular disease; Obstructive sleep apnea syndrome; CPAP;

In the present study, we investigated whether nitric oxide (NO) could be involved in the effects of arg-vasopressin (AVP) on osteoblast-like cells. Cells derived from endothelial nitric oxide synthase (eNOS)-knockout mice and their wild type (WT) counterparts, and an osteosarcoma cell line (SaOS-2) were used. AVP (10–100 pmol/l) increased proliferation of osteoblast-like cells from WT mice. The effect was abolished by an AVP V1-receptor antagonist. AVP increased proliferation of cells from eNOSKO mice only when a NO donor, SNAP, was added. A nitric oxide synthase-inhibitor, L-NAME, antagonized the increase in cell proliferation in response to AVP in SaOS-2 cells. In conclusion, this study indicates that NO is involved in the effects of AVP on cell proliferation in osteoblast-like cells.
Keywords: Arg-vasopressin; Endothelial NOS; NO; Knockout mouse; SaOS-2 cells; Osteoblast-like cells; L-NAME; SNAP;

Endomorphins interact with tachykinin receptors by Piotr Kosson; Iwona Bonney; Daniel B. Carr; Andrzej W. Lipkowski (1667-1669).
Soon after the discovery of endomorphins several studies indicated differences between pharmacological effects of endomorphins and other MOR selective ligands, as well as differences between the effects of endomorphin I and endomorphin II. We now propose that these differences are the result of an additional non-opioid property of endomorphins, namely, their weak antagonist properties with respect to tachykinin NK1 and NK2 receptors.
Keywords: Endomorphin; Tachykinin antagonist;

The role of adrenomedullin in angiogenesis by Domenico Ribatti; Beatrice Nico; Raffaella Spinazzi; Angelo Vacca; Gastone G. Nussdorfer (1670-1675).
Adrenomedullin (AM) is a 52 amino acid peptide originally isolated from human pheochromocytoma. It was initially demonstrated to have profound effects in vascular cell biology, since AM protects endothelial cells from apoptosis, promotes angiogenesis and affects vascular tone and permeability. This review article summarizes the literature data concerning the relationship between AM and angiogenesis and describes the relationship between vascular endothelial growth factor, hypoxia and AM and tumor angiogenesis. Finally, the role of AM as a potential target of antiangiogenic therapy is discussed.
Keywords: Adrenomedullin; Angiogenesis; HIF; Tumor progression; VEGF;

Calcitonin gene-related peptide and hypertension by Pan-Yue Deng; Yuan-Jian Li (1676-1685).
Capsaicin-sensitive sensory nerves participate in the regulation of cardiovascular functions both in the normal state and the pathophysiology of hypertension through the actions of potent vasodilator neuropeptides, including calcitonin gene-related peptide (CGRP). CGRP, a very potent vasodilator, is the predominant neurotransmitter in capsaicin-sensitive sensory nerves, and plays an important role in the initiation, progression and maintenance of hypertension via: (1) the alterations in its synthesis and release and/or in vascular sensitivity response to it; (2) interactions with pro-hypertensive systems, including renin–angiotensin–aldosterone system, sympathetic nervous system and endothelin system; and (3) anti-hypertrophy and anti-proliferation of vascular smooth muscle cells. The decrease in CGRP synthesis and release contributes to the elevated blood pressure, as shown in the spontaneously hypertensive rats, α-CGRP knockout mice, Dahl-salt or phenol-induced hypertensive rats. In contrast, the increase in CGRP levels or the enhancement of vascular sensitivity response to CGRP plays a beneficial compensatory depressor role in the development of hypertension, as shown in deoxycorticosterone-salt, sub-total nephrectomy-salt, N ω-nitro-l-arginine methyl ester or two-kidney, one-clip models of hypertension in rats. We found that rutaecarpine causes a sustained depressor action by stimulation of CGRP synthesis and release via activation of vanilloid receptor subtype 1 (VR1) in hypertensive rats, which reveals the therapeutic implications of VR1 agonists for treatment of hypertension.
Keywords: Calcitonin gene-related peptide (CGRP); Hypertension; Sensory nerve; Renin–angiotensin–aldosterone system; Sympathetic nervous system; Endothelin;