Acute and nongenomic effects of testosterone on isolated and perfused rat heart

Gonadal steroid hormones influence vascular tone and the development of hyp ertension. There are sex differences in the incidence of cardiovascular dis eases, and great attention has been placed on the study of estrogen cardiov ascular effects. However, there are only a few reports on the effects of te stosterone on the vasculature. It is commonly accepted that the mechanism o f the action of steroid hormones on tar et tissues is mediated through the binding of hormones to cytoplasmic or nuclear receptors. However, some stud ies indicate that steroid action can be extremely rapid and therefore unlik ely to be through a genomic mechanism. The purpose of this study was to ass ess the effect of intravascularly confined testosterone on an isolated rat heart to demonstrate acute and possibly nongenomic effects of the steroid. Our results show that testosterone blocked the adenosine vasodilator effect and increased vascular resistance, even when its presence was restricted t o the coronary vascular lumen. These effects were exerted rapidly and possi bly through nongenomic mechanisms.