INTRACELLULAR FREE-MAGNESIUM LEVELS IN VASCULAR SMOOTH-MUSCLE AND STRIATED-MUSCLE CELLS OF THE SPONTANEOUSLY HYPERTENSIVE RAT

In humans with essential hypertension and in spontaneously hypertensive rats (SHR), insulin resistance may be present even in lean individuals. As the basis for this abnormality is unknown, we have used a newly developed fluorophore to measure intracellular free-Mg2+ concentrations in cultured aortic vascular smooth muscle cells and striated muscle cells from SHR and normotensive Wistar Kyoto (WKY) rats. Intracellular free-Mg2+ levels were lower in both striated muscle cells (SHR, 0.423 ± 0.077 mmol · L-1 v WKY, 0.559 ± 0.068 mmol · L-1; P < .001) and vascular smooth muscle cells (SHR, 0.406 ± 0.067 mmol · L-1 v WKY, 0.625 ± 0.077 mmol · L-1; P < .001) from hypertensive animals. This widespread, intrinsic defect in the regulation of intracellular Mg2+ may explain the increased vascular resistance and reduced insulin sensitivity present in hypertension. © 1992.