Vasoconstrictor products of cyclo-oxygenase activity limit acetylcholine-induced cutaneous vasodilatation in young men.
In healthy young men (age, 20-22 years), we tested the role of prostanoids produced by the COX (cyclo-oxygenase) pathway in cutaneous vasodilatation evoked in the finger by ACh (acetylcholine). To this end, changes in cutaneous RCF (red cell flux), recorded by the laser Doppler technique, evoked by a series of iontophoretic pulses of ACh were tested before and after oral aspirin (600 mg). Increases in RCF produced by successive pulses of ACh up to a mean change of 125.5 +/- 11.8 PU (perfusion units) were potentiated 30 min after aspirin (160.0 +/- 12.4 PU; P < 0.05). By contrast, aspirin had no effect on increases in RCF evoked by iontophoretic application of the NO (nitric oxide) donor and endothelium-independent dilator sodium nitroprusside (mean increases in RCF were 73.8 +/- 9.8 PU before and 79.1 +/- 12.2 PU after aspirin). The ACh-evoked increases in RCF were also potentiated 3 h after oral administration of the antioxidant vitamin C (1000 mg; 139.1 +/- 15.4 PU before and 170.5 +/- 13.5 PU after vitamin C; P < 0.05). We propose that, in healthy young men, cutaneous vasodilatation evoked in the finger by the endothelium-dependent dilator ACh is limited by constrictor products of the COX pathway, including PGH2 (prostaglandin H2), TXA2 (thromboxane A2) and/or superoxide anions. This effect of the COX products may be an early marker of the increased risk of cardiovascular disease in men compared with women.
Hendry
Ross G
RG
Department of Physiology, Division of Medical Sciences, The Medical School, Birmingham B15 2TT, UK.
Marshall
Janice M
JM
D000109:Acetylcholine; D000328:Adult; D000704:Analysis of Variance; D001205:Ascorbic Acid / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects; D005385:Fingers; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007478:Iontophoresis; D017078:Laser-Doppler Flowmetry; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D012867:Skin / Q000098:blood supply* / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents
D016861:Cyclooxygenase Inhibitors; D014665:Vasodilator Agents; D009599:Nitroprusside; D011451:Prostaglandin-Endoperoxide Synthases; D000109:Acetylcholine; D001205:Ascorbic Acid; D001241:Aspirin; D009638:Norepinephrine