Decreased intracellular phosphate content in vascular smooth muscle cells from spontaneously hypertensive rats (SHR)

An alteration of phosphate concentrations and ATP metabolism seem to be involved in the pathogenesis of primary hypertension. Only sparse data exist concerning intracellular phosphate concentrations in hypertensive cells. For these reasons in aortic smooth muscle cells from 10 spontaneously hypertensive rats (SHR) of the Munster strain and 10 normotensive Wistar-Kyoto rats (WKY) aged 8-10 months, the intracellular phosphate content was measured by electron probe X-ray microanalysis (Camscan CS 24 apparatus, Cambridge, U.K.). Measurements were performed in aortic cryosections 3 mu m thick; the phosphate content was 15.81 +/- 1.22 g/kg dry weight in SHR versus 23.6 +/- 0.79 g/kg dry weight in WKY (means +/- s.d., p < 0.01). Thus, aortic smooth muscle cells from SHR are characterized by a markedly decreased intracellular phosphate content compared with normotensive cells. This may either be due to genetically determined disturbances in transmembrane phosphate transport or an increased phosphate turnover. Intracellular phosphate handling may be disturbed in SHR aortic smooth muscle as it is in hypertensive blood cells.