Renin immunochemistry, sodium excretion and relative heart weight in cyclosporine- or alimentary-induced magnesium deficiency in rats.

Rats were given a magnesium-(Mg) depleted (Mgd), or a Mg-standard (Mgst) or a Mg-enriched (Mge) diet, with 20 mg/kg/day cyclosporine (Cy) or olive oil per os for 90 days (6 groups). Anti-renin antibody was applied and the percent of renin-positive glomeruli (RI) was taken. Sodium excretion (NaU), relative heart weight (HW), as a measure of hypertension, and total femur Mg were measured. Compared to dietary controls, femur Mg was reduced under Cy and Mgd or Mgst indicating Mg deficiency. RI was higher in all Cy groups (p < 0.01), and Nau was lower in Mgd + Cy and in Mgst + Cy (p < 0.01). Correspondingly, HW was found to be significantly higher in Mgd + Cy and Mgst + Cy. In animals under Mge + Cy, there were no differences in NaU and HW compared to controls. The results indicate a relation between Cy-related hypertension and Mg status: Mg deficiency seems to enhance the hypertensive effect of Cy via sodium retention.