Calcium uptake and enzymatic activities were studied on plasma membrane-enriched and other subcellular fractions from mesenteric arteries of normotensive Wistar (NWR) and spontaneously hypertensive rats (SHR). The specific activities of plasma membrane marker enzymes (5’-nucleotidase, phosphodiesterase I, leucine aminopeptidase, and ouabain-sensitive K+-activated phosphatase) were significantly greater in the plasma membrane-enriched fraction from arteries of hypertensive than in those from normotensive rats. Alkaline phosphatase and Mg++-ATPase exhibited increased activities in all subcellular fractions of arteries from SHR as compared to those from NWR. The maximum calcium uptake in the presence of 5 mM ATP and 17 µM free calcium by the plasma membrane fraction from SHR arteries was significantly greater than that from NWR arteries. In contrast, the maximum ATP-independent calcium uptake in the presence of 1 mM free calcium by the plasma membrane fraction from SHR arteries was significantly lower than that from NWR arteries. The ionophore-induced decrease in calcium uptake by these fractions was 1.5–2.5 times greater for SHR than for NWR arteries. The presence of changes in activities of enzymes believed to be involved in
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Wei et al. (2008) studied this question.