Platelet and erythrocyte membrane microviscosity in Lyon hypertensive rats

The altered membrane microviscosity demonstrated in various cells of spontaneously hypertensive rats (SHR) and essential hypertensive (EH) patients has been proposed to play an important role in the pathogenesis of genetic forms of hypertension. The aim of this study was to evaluate possible changes of membrane microviscosity in platelets and red cell 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 membrane microviscosity. On the other hand, there were no changes in TMA-DPH fluorescence anisotropy that characterizes the dynamic properties of the outer membrane leaflet. DPH, but not TMA-DPH, anisotropy correlated negatively with blood pressure. This was true for both red cell ghosts and platelets. Membrane microviscosity had no significant relationship to plasma cholesterol or triglycerides. In platelets, TMA-DPH anisotropy correlated positively with cytosolic free calcium concentration ([Ca2+]i). A similar trend was observed in erythrocytes. In contrast, DPH anisotropy had an inverse relationship to platelet [Ca2+]i. It can be concluded that the alterations of membrane microviscosity seen in LH rats are completely different from those reported in SHR animals and that surface and core membrane microviscosity differ in their relationship to blood pressure and [Ca2+]i.