Age dependent decreased intracellular Mg++ concentrations in vascular smooth muscle cells of the abdominal aorta from normotensive (WKY) and spontaneously hypertensive rats (SHR)

Whereas in blood cells decreased magnesium concentrations in essential hype rtension have often been described only sparse data exist on intracellular magnesium content and exchange in vascular smooth muscle cells. Therefore in aortic smooth muscle cells from 10 spontaneously hypertensive rats (SHR) of the Munster strain and 10 normotensive Wistar-Kyoto rats (WKY ) aged 1 and 3 and 8-10 months, the intracellular magnesium content was mea sured. Electron-probe X-ray microanalysis was used to determine intracellular Mg+ concentrations in aortic cryosections 3 mu m thick. The magnesium ion cont ent was 42 +/- 8 mmol/kg dry weight in SHR versus 44 +/- 7 mmol/kg dry weig ht in WKY aged 1 month, 47 +/- 13 mmol/kg dry weight in SHR versus 48 +/- 1 9 mmol/kg dry weight in WKY aged 3 months and 37 +/- 6 mmol/kg dry weight i n SHR versus 47 +/- 4 mmol/kg dry weight in WKY aged 8-10 months (p < 0.05) . Aortic smooth muscle cells from SHR are characterized by a significantly lo wered intracellular magnesium ion content in 8-10 months old animals as com pared with aged matched normotensive animals. The results may be due to gen etically determined disturbances in transmembrane magnesium transport syste ms. Additionally, a subgroup of young SHR exists showing low intracellular Mg++ concentrations with an age of 1 and 3 months, a hen hypertension becom es established. In conclusion, cellular magnesium handling may be disturbed in SHR aortic s mooth muscle cells, analogously to alterations in human blood cells from es sential hypertensive patients.