Evidence of altered calcium accumulation and calcium binding by the membranes of adipocytes in spontaneously hypertensive rats.

Calcium accumulation and calcium binding (ATP--dependent and ATP-independent calcium uptake) by the fragmented plasma membrane, the cytoplasmic reticulum and the mitochondria of isolated adipocytes obtained from spontaneously hypertensive (SHR, Kyoto-Wistar) and normotensive Wistar and Kyoto-Wistar rats were studied by means of isotopic (45Ca) exchange in vitro. The value of ca accumulation in the cytoplasmic reticulum fraction of adipocytes obtained from SHR was found decreased, while in the mitochondrial fraction it was considerably greater as compared to those in both normotensive control groups. Ca binding (ATP independent) by the plasma membrane fraction of hypertensive rats was less than that of the normotensive rats. There was no difference between the groups studied in calcium binding ability for the cytoplasmic reticulum fraction of adipocytes. These results seem to indicate that the adipose cells of hypertensive rats have an alteration of the membrane mechanism maintaining intracellular calcium distribution.