MAGNESIUM AND SODIUM-ION CONTENT OF VASCULAR SMOOTH-MUSCLE CELLS FROMNORMOTENSIVE (WKY) AND SPONTANEOUSLY HYPERTENSIVE (SHR) RATS

In different kinds of human or animal blood cells lowered intracellula r Mg++ and increased Naf concentrations, possibly due to an increased activity of a Mg++-Na+-exchanger, have been described in essential hyp ertension. Therefore, in aortic smooth muscle cells from 10 spontaneou sly hypertensive (SHR) rats of the Munster strain and 10 normotensive (WKY) control animals aged 8 - 10 months, the intracellular magnesium and sodium ion content were measured by electron-probe X-ray microanal ysis, quantified by the method of Hall. In SHR the vascular smooth mus cle Mg++ content was 37 +/- 6 versus 47 +/- 4 mmol/kg dry weight in WK Y (p < 0.05). In WKY vascular smooth muscle sodium ion content was mea sured 289 +/- 17 versus 548 +/- 39 mmol/kg dry weight in SHR (p < 0.01 ). In conclusion, aortic smooth muscle cells from SHR are characterize d by a markedly lowered intracellular magnesium ion content and increa sed sodium ion concentrations compared with normotensive cells. The re sults indicate a possible role for a Mg++-Na+-exchanger or genetically determined disturbances in transmembrane magnesium and sodium ion tra nsport systems in essential hypertension.