Diffuse structural alterations in cell membranes of spontaneously hypertensive rats

Plasma membranes from heart, nerve endings, and liver were compared in 3-week-old male spontaneously hypertensive rats from the Okamoto substrain (SHR) and normotensive Wistar/Kyoto control rats (WKY) [systolic blood pressure 105 +/- 4 and 95 +/- 4 mm Hg, respectively (1 mm Hg = 133 Pa)] according to two criteria: calcium binding at physiological intracellular concentrations and polarization of an embedded fluorescent probe, 1,6-diphenyl-1,3,5-hexatriene. Whatever the tissue of origin, the density of high-affinity calcium binding sites was lower in SHR than in WKY plasma membranes, and the polarization of diphenylhexatriene fluorescence was constantly higher in SHR than in WKY membranes. These membrane abnormalities are similar to those previously described in the erythrocyte membrane from SHR. The presence of diffuse structural alterations in cellular membrane from young spontaneously hypertensive rats when blood pressure is still in the normotensive range suggests a genetic origin. Such inherited abnormalities may by themselves participate in the rise in blood pressure.