PLATELET MEMBRANE MICROVISCOSITY IN SABRA RATS WITH EARLY SALT HYPERTENSION

1. To investigate the possibility that arterial hypertension is associ ated with changes in the physicochemical properties of cell membranes, we have studied the effects of dietary salt loading on platelet membr ane microviscosity in hypertension-prone and -resistant Sabra rats. 2. Sixteen hypertension-prone and 14 hypertension-resistant Sabra rats w ere submitted to either a low-salt (0.25% NaCl) or a high-salt (4% NaC l) diet for 3-4 weeks. Platelet membrane anisotropy was determined, in the presence and absence of extracellular Na+, using two fluorescent probes, diphenylhexatriene and trimethylamino-diphenylhexatriene, inse rted in different areas of the cell membranes. 3. A decrease in diphen ylhexatriene anisotropy was demonstrated when platelets of hypertensio n-prone (but not hypertension-resistant) Sabra rats were suspended in a Na+-free medium. This alteration in membrane dynamic properties is l ocalized within the hydrophobic core of the platelet membranes and is independent of salt intake. It reflects an abnormal fluidizing effect of extracellular Na+ removal.