Reduced calcium binding capacity is an intrinsic abnormality of red blood cell membrane in spontaneously hypertensive rats.

Reduced calcium (Ca) binding capacity is a widespread and primary abnormality in SHR. It was reported that in red blood cell (RBC) membranes it is detectable only in membrane preparations containing sealed inside-out vesicles, the formation of which implies the partial removal of cytoskeletal proteins from the RBC membrane. The present study compares the Ca binding capacity of RBC membrane preparations with normal (+CS) and reduced (-CS) cytoskeleton content in SHR and normotensive WKY control rats. In addition to Ca binding capacity and protein content, the cholesterol content and the acetylcholinesterase (ACE) activity were measured as having a quantitative measure of integral membrane components in the different membrane preparations. In both strains the cholesterol/protein ratio, the ACE activity per mg of membrane protein, and the Ca binding capacity were all significantly higher in -CS compared to +CS membrane preparations (P less than .001). A statistically significant difference in Ca binding capacity between SHR and WKY was observed only using -CS membranes preparation. The results support the concept of a reduced membrane Ca binding capacity in rat genetic hypertension: this abnormality is detectable only in membrane preparations with reduced cytoskeletal content.