title: Effects of cyclooxygenase inhibition on vascular responses evoked in fingers of men and women by iontophoresis of 1- and 2-adrenoceptor agonists.
abstract: In 10 men and nine women aged 20-23 years, we aimed to establish whether endogenous prostanoids synthesised by cyclooxygenase (COX) affect responses evoked in the finger by α(1)- or α(2)-adrenoceptor agonists. Cutaneous red cell flux (cRCF) was recorded in dorsal finger during iontophoresis of phenylephrine (PE) or clonidine (0.5 mm, seven 0.1 mA pulses followed by one 0.2 mA pulse: 30 s each at 60 s intervals) before and after the COX inhibitor aspirin (600 mg p.o.). In men, PE evoked a biphasic mean increase/decrease in cRCF before but a monophasic mean decrease in cRCF of 30-40% after aspirin (P < 0.05). In women in the low oestrogen (E(2)) phase of the menstrual cycle, PE evoked a decrease in cRCF (30-40%; P < 0.05) that was unchanged by aspirin, whereas in the high E(2) phase, PE evoked no change before but a graded decrease in cRCF (30-40%; P < 0.05) after aspirin. Clonidine evoked a decrease in cRCF (∼30%; P < 0.05) in men before, but not after, aspirin. Clonidine evoked both increases and decreases in cRCF before and after aspirin in women in the low and high E(2) phases (P > 0.05). We propose that finger vasoconstriction evoked by extraluminal α(1)-adrenoceptor stimulation is blunted by vasodilator COX products in young men and overcome by their action in women in the high, but not low E(2), phase of the menstrual cycle. By contrast, α(2)-adrenoceptor stimulation evokes finger vasoconstriction that is mediated by vasoconstrictor COX products in young men, but evokes no consistent response in women in the low or high E(2) phases of the menstrual cycle.
authors.affiliation: School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Amar
authors.initials: A
authors.lastname: Srinivasa
authors.forename: Janice M
authors.initials: JM
authors.lastname: Marshall
mesh_terms: D058646:Adrenergic alpha-1 Receptor Agonists / Q000494:pharmacology*; D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004967:Estrogens / Q000502:physiology; D005260:Female; D005385:Fingers / Q000098:blood supply*; D006801:Humans; D007478:Iontophoresis; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects* / Q000502:physiology; D012727:Sex Characteristics; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
chemical_list: D058646:Adrenergic alpha-1 Receptor Agonists; D058647:Adrenergic alpha-2 Receptor Agonists; D016861:Cyclooxygenase Inhibitors; D004967:Estrogens; D010656:Phenylephrine; D003000:Clonidine; D001241:Aspirin