Intracellular Electrolytes in Essential Hypertension during Treatment with Torasemide

Abstract

Diuretics do play an important role in the treatment of hypertension. But still the mechanism of the blood pressure lowering effect of diuretics in hypertension is not entirely clarified. Whereas the reduction in blood volume and consequently in stroke volume can be demonstrated initially, this is not found during long term treatment. On the other hand a decrease in total peripheral resistance has been described, which may be responsible for the long term reduction in blood pressure (1). The mechanism, by which diuretics influence vascular tone, is still unknown. In this context the direct action of diuretics on the pathogenetic factors in essential hypertension may be suspected. Among those interest has focussed on intracellular free calcium in arterial smooth muscle cells and other tissues in the last years. Such an increase in intracellular free calcium which has been demonstrated in red blood cells from essential hypertensives and from spontaneously hypertensive rats as well as in arterial smooth muscle cells from spontaneously hypertensive rats (2) can be expected to cause vasoconstriction by the well known effect of calcium on electromechanical coupling in contractile tissues. Therefore the effect of a loop diuretic on intracellular free calcium was examined. Furthermore intracellular natrium in red blood cells was measured, as the diuretic induced natriuresis can be expected to alter intracellular natrium stores.