GENDER AFFECTS RENAL VASOCONSTRICTOR RESPONSE TO ANG-I AND ANG-II

This study tested the hypothesis that gender affects the presser and r enal vasoconstrictor responses to angiotensin (Ang) I and Ang II in sa lt-replete normotensive subjects. Ang I and Ang II were infused in gra ded doses into 9 men and 8 women in a randomized, single-blind, crosso ver study. There were no differences between genders in baseline blood pressure, heart rate, sodium excretion, renal plasma now, angiotensin -converting enzyme (ACE) genotype, ACE activity, plasma renin activity , aldosterone, or Ang II levels. Although presser responses to Ang I a nd Ang II were similar in men and women, there was a negative relation ship between the change in mean arterial pressure and the change in he art rate during Ang I and II infusion in women only. The half-time of the presser response alter discontinuation of Ang I but not Ang II inf usion was greater in men than in women (9.5+/-2.2 versus 4.3+/-2.1 min utes, P<.05). This difference in duration did not result from gender d ifferences in the metabolism of Ang I because Ang II levels measured d uring Ang I infusion were identical in men and women. In contrast, the renal vasoconstrictor response to Ang I and Ang II was significantly increased in women compared with that in men (Ang I, -243+/-31 versus -138+/-13 U/1.73 m(2); Ang II, -233+/-25 versus -175+/-18 U/1.73 m(2); P<.03). These data suggest an effect of gender on baroreflex reactivi ty during angiotensin infusion. Moreover, in the setting of similar An g II concentrations, the dramatic difference in the renal vasoconstric tor responses to Ang I and Ang II between salt-replete men and salt-re plete women suggests gender differences at a pharmacodynamic level.