ALTERATIONS OF MEMBRANE-PROPERTIES IN ERYTHROCYTES OF SALT HYPERTENSIVE SABRA RATS

This study was designed to investigate the effects of a hypertensive s timulus, high salt intake, in hypertension-prone (SBH) and -resistant (SBN) Sabra rats on erythrocyte Na+ content (Na-i(+)), Ca2+ influx and cytosolic Ca2+ concentration ([Ca2+](i)). The relationships of these parameters to plasma lipids, circulating digoxin-like immunoreactivity and membrane microviscosity, determined by the fluorescence anisotrop y of trimethylamino-diphenylhexatriene (TMA-DPH) and diphenylhexatrien e (DPH), were also evaluated. Erythrocytes of SBH rats were characteri zed by increased [Ca2+](i), unchanged Ca2+ influx and reduced Na-i(+), There were no significant differences in the plasma digoxin-like immu noreactivity between the two strains. High-salt intake decreased membr ane microviscosity (DPH anisotropy) in SBH rats but did not alter the above parameters. Erythrocyte [Ca2+](i) correlated positively with dia stolic blood pressure and negatively with erythrocyte Na-i(+). Membran e dynamics evaluated by the two fluorescent probes did not correlate w ith [Ca2+](i), Ca2+ influx or Na-i(+) whereas DPH anisotropy was inver sely related to blood pressure. These relationships were independent o f plasma cholesterol or triglycerides. It can be concluded that 1) sim ilarly to earlier observations in essential hypertension and spontaneo usly hypertensive rats, erythrocyte [Ca2+](i) correlates positively wi th blood pressure in salt-dependent hypertension, and 2) increased ery throcyte Na+ content need not be a hallmark of hypertension.