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The effects of the vasoactive perivascular neuropeptides calcitonin gene-related peptide (CGRP), neurokinin A (NKA), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP) on proliferation of cultured human umbilical vein endothelial cells (HUVECs) were investigated. CGRP was shown to increase both cell number and DNA synthesis, whereas NKA, NPY, and VIP were ineffective. l I-labeled CGRP was shown to bind to HUVECs and this binding was displaced by addition of unlabeled CGRP, suggesting the existence of specific CGRP receptors. The effect of CGRP on formation of adenosine 3',5'-cycdic monophosphate (cAMP) and inositol phosphates (InsP), two intracellular messengers known to be involved in regulation of cell proliferation, was investigated. CGRP stimulated cAMP formation but was without effect on the formation of InsP. Proliferation, as well as cAMP formation, was also stimulated by cholera toxin. Basic fibroblast growth factor stimulated growth without affecting cAMP or InsP formation, whereas thrombin, which increased InsP formation, did not stimulate proliferation. We thus suggest that CGRP may act as a local factor stimulating proliferation of endothelial cells; that the mechanism of action is associated with cAMP formation; and that this effect of CGRP may be important for formation of new vessels during physiological and pathophysiological events such as ischemia, inflammation, and wound healing. Several different factors have been shown to stimulate the formation of new vessels, angiogenesis, and/or to be mitogenic for cultured endothelial cells. These factors include polypeptide growth factors-i.e., basic and acidic fibroblast growth factor (bFGF, aFGF)-endothelial cell growth factor, which is a precursor form of aFGF, transforming growth factors a and /3, angiogenin, and tumor necrosis factor a (1).Angiogenic factors may be important when released locally by cells adjacent to the endothelium, possibly also produced by the endothelial cells themselves or as circulating factors in plasma.Indirect evidence has suggested trophic effects of peripheral neurons. In the newt, naturally occurring limb regeneration is prevented by damage to the peripheral nerve innervating the limb (2). Intact sensory innervation has been shown to be important for corneal wound healing in the rat (3), and in humans suffering from Parry-Romberg syndrome, a marked hemifacial dystrophia is observed in the area innervated by the trigeminal nerve (4). Although direct evidence from in vivo studies is essentially lacking, recent studies have shown that sensory neuropeptides regulate cell proliferation in vitro. Neurokinin A (NKA) and substance P (SP), which are structurally related, have been shown to induce proliferation of human fibroblasts and rat smooth muscle cells (5). This effect was shown to be parallel with increased phosphatidylinositol (PI) turnover (6). Furthermore, vasoactive intestinal polypeptide (VIP) has been shown to inhibit serum-induced proliferation of rat smooth muscle cells and to stimulate prol...

Background: Cyclooxygenase inhibiting nitric oxide donators (CINODs) are a new class of antiinflammatory and analgesic drugs that may minimise gastrointestinal toxicity compared with standard non-steroidal anti-inflammatory drugs (NSAIDs) by virtue of nitric oxide donation. Methods: A proof of concept study of the gastrointestinal safety of AZD3582, the first CINOD available for human testing, was conducted. Thirty one subjects were randomised to receive placebo, naproxen 500 mg twice daily, or its nitroxybutyl derivative AZD3582 in an equimolar dose (750 mg twice daily) for 12 days in a double blind three period crossover volunteer study. At the start and end of each dosing period, gastroduodenal injury was assessed by endoscopy and small bowel permeability by differential urinary excretion of lactulose and L-rhamnose. Pharmacokinetic profiles were assessed at steady state. Results: On naproxen, the mean total number of gastroduodenal erosions was 11.5 (and one subject developed an acute ulcer) versus 4.1 on AZD3582 (p,0.0001). More than half of the subjects had no erosions on AZD3582. Differences were seen for both the stomach and duodenum. Naproxen increased intestinal permeability (lactulose:L-rhamnose ratio 0.030 before v 0.040 after treatment) whereas AZD3582 (0.029 before, 0.029 after; p = 0.006 v naproxen) and placebo (0.030 before, 0.028 after; p,0.001 v naproxen) did not. The steady state bioavailability of naproxen metabolised from AZD3582 was 95% (95% confidence interval 87-101%) of that after naproxen administration. Conclusions: This human study supports animal data showing reduced gastrointestinal toxicity with the CINOD AZD3582. The potential combination of effective pain relief and gastrointestinal protection offered by AZD3582 warrants further evaluation in human clinical studies.

An increasing body of evidence has suggested trophic effects of peripheral nerves. In this study, the growth stimulatory properties of the sensory neuropeptides vasoactive intestinal polypeptide (VIP), substance P (SP), calcitonin generelated peptide (CGRP), and somatostatin (SOM) on cultured human keratinocytes were investigated. It was shown that VIP, in the presence of lethally treated 3T3 fibroblast feeder cells and epidermal growth factor (EGF), stimulated proliferation of keratinocytes in a dose-dependent manner, whereas SP, CGRP, and SOM were ineffective. VIP stimulated adenylate cyclase activity in membranes obtained from cultured keratinocytes in a dose-dependent manner, indicating an involvement of cAMP as second messenger in this reaction. Furthermore, '25I-labeled VIP was shown to bind to cultured keratinocytes and this binding could be displaced by addition of unlabeled VIP, suggesting the presence of specific receptors. It is therefore possible that VIP, released from sensory nerve endings in the skin, may act as a local mitogenic factor for human keratinocytes by stimulating adenylate cyclase activity via specific VIP receptors.

In a study to characterise the chest pain induced by adenosine this agent was given as a bolus into a peripheral vein to six healthy volunteers (five men) aged 30-44. On the first day the maximum tolerable dose was determined in each case. On the second day three doses of adenosine (one third, two thirds, and the full maximum tolerable dose) and three doses of saline were given single blind in randomised order. Thereafter aminophylline 5 mg/kg was given and the procedure repeated in a different randomised order. On the third day between two thirds and the full maximum tolerable dose was given followed by 10 mg dipyridamole intravenously and a second injection of the same dose of adenosine. Heart rate and atrioventricular blocks were recorded by electrocardiography. One minute after each dose of adenosine the chest pain was scored.The maximum tolerable dose of adenosine ranged from 10-6 to 37-1 mg. All subjects experienced uneasy central chest pain provoking anxiety. The pain radiated to the shoulders, ulnar aspect ofthe arms, epigastric area, back, and into the throat. The pain began about 20 seconds after the injection and lasted 10-15 seconds. Increasing the dose of adenosine increased the intensity of the pain. Administration of aminophylline reduced the pain significantly. Second degree heart block was recorded in