Volume 3, Number 2, June 2002

Lack of rapid aldosterone effects on forearm resistance vasculature in health
Prasad Gunaruwan, Matthias Schmitt, Justin Taylor, Leong Lee, Allan Struthers, Michael Frenneaux

Objectives: Systemic infusions of aldosterone cause an acute increase in systemic vascular resistance (SVR) in healthy subjects. It is not clear whether this is due to a direct effect on the vasculature or the result of increased sympathetic tone. We investigated the short-term effects of locally infused aldosterone on the forearm resistance bed.
Methods: In this dose response study, we assessed the effects of incremental doses (10, 50, 100 ng/minute) of intrabrachial aldosterone on forearm blood flow (FBF), using conventional strain gauge plethysmography. Arterial blood pressure was monitored continuously, using finger photo- plethysmography. Forearm vascular resistance (FVR) was calculated. FBF and FVR were also measured in the non-infused arm. Changes in FBF and FVR in the infused arm were corrected for those occurring in the control arm.
Results: Plasma aldosterone levels in the venous effluent of the infused arm increased in a dose-dependent fashion, from 113.3±17.9 pg/ml at baseline to 297.8±51.8 pg/ml at 10 ng/minute (p=<0.01), 743.9±105.9 pg/ml at 50 ng/min (p=<0.001 vs. baseline) and 1230.6±73.7 pg/ml at 100 ng/min (p=<0.0005 vs. baseline). Plasma concentrations of aldosterone in the control arm did not change significantly vs. baseline. The corrected FBF (+4.1±10.3%) and corrected FVR (+4.3±11.3%) did not change significantly even at peak infusion rates.
Conclusions: Local intra-arterial infusion of aldosterone had no acute effect on forearm resistance vessels in healthy male volunteers.

JRAAS 2002;3:123-125.

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