PLATELET AND ERYTHROCYTE-MEMBRANE MICROVISCOSITY IN LYON HYPERTENSIVERATS

The altered membrane microviscosity demonstrated in various cells of s pontaneously hypertensive rats (SHR) and essential hypertensive (EH) p atients has been proposed to play an important role in the pathogenesi s of genetic forms of hypertension. The aim of this study was to evalu ate possible changes of membrane microviscosity in platelets and red c ell ghosts of Lyon hypertensive (LH) and normotensive (LN) rats. Both erythrocyte and platelet membranes of LH rats had a clear tendency to reduced DPH fluorescence anisotropy reflecting the decreased core memb rane microviscosity. On the other hand, there were no changes in TMA-D PH fluorescence anisotropy that characterizes the dynamic properties o f the outer membrane leaflet. DPH, but not TMA-DPH, anisotropy correla ted negatively with blood pressure. This was true for both red cell gh osts and platelets. Membrane microviscosity had no significant relatio nship to plasma cholesterol or triglycerides. In platelets, TMA-DPH an isotropy correlated positively with cytosolic free calcium concentrati on ([Ca2+](i)). A similar trend was observed in erythrocytes. In contr ast, DPH anisotropy had an inverse relationship to platelet [Ca2+](i). It can be concluded that the alterations of membrane microviscosity s een in LH rats are completely different from those reported in SHR ani mals and that surface and core membrane microviscosity differ in their relationship to blood pressure and [Ca2+](i).