EFFECTS OF DEHYDROEPIANDROSTERONE-SULFATE ON CELLULAR CALCIUM RESPONSIVENESS AND VASCULAR CONTRACTILITY

Dehydroepiandrosterone sulfate (DHEAS) is an endogenous steroid having a wide variety of biological effects, but its physiological role remains undefined. Since an age-related decline of DHEAS corresponds to the progressive onset of atherosclerosis, cardiovascular diseases, and overall mortality, we investigated a possible protective role of DHEAS in vascular disease by studying the effects of this hormone (10(-7) to 10(-5) mol/L) on cytosolic free calcium and contractility in different in vitro vascular tissue preparations. DHEAS produced a significant, dose-dependent relaxation of isolated helical strips of rat tail artery precontracted with KCl (60 mmol/L) (89.7+/-18.7%; P<.01), arginine vasopressin (3 nmol/L) (27.3+/-7.1%, P<.01), and norepinephrine (0.1 mu mol/L) (49.2+/-18.2%, P<.01). In isolated vascular smooth muscle cells DHEAS reversibly inhibited KCl (30 mmol/L)-induced elevations of cytosolic free calcium to 69.8+/-8.4% and 43.8+/-7.4% of the control response at 5x10(-7) and 5x10(-6) mol/L, respectively (P<.05 at both doses). These results provide evidence of a direct vascular action of DHEAS, in doses reflecting circulating levels in vivo, and suggest the possibility that these effects are mediated by modulation of intracellular calcium metabolism. We hypothesize that physiologically, DHEAS may serve to buffer vascular responsiveness to a wide variety of depolarizing and constrictor hormonal stimuli.