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Non-technical summary Sympathetic nerve fibres in the fingers release noradrenaline, which has the potential to act on α 1 -or α 2 -adrenoreceptors on the blood vessels. We used iontophoresis, which generates a tiny electrical charge, to push selective α 1 -or α 2 -receptor agonists through the skin and recorded changes in finger blood flow before and after aspirin, which inhibits cyclooxygenase (COX), an enzyme which synthesises vasodilator and vasoconstrictor prostaglandins. Our results yielded the novel findings that finger vasoconstriction produced by α 1 -adrenoceptors is blunted by locally synthesised vasodilator COX products in young men and in young women in the high but not the low oestrogen phase of the menstrual cycle. By contrast, finger vasoconstriction evoked by α 2 -adrenoceptors is largely attributable to vasoconstrictor COX products in young men, but overcome by vasodilator COX products in young women. This provides a foundation for testing whether COX products similarly modify vasoconstriction evoked by changes in sympathetic nerve activity.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.

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Comparison of postoperative outcomes between donation after circulatory death and donation after brain death liver transplantation using the comprehensive complication index.

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