Aldosterone binding to mineralocorticoid receptors of mononuclear leukocytes in diabetic subjects

Abstract

We present the characteristic features of mineralocorticoid receptor regulation in human mononuclear leukocytes in patients with diabetes mellitus. Eighteen diabetic patients (3M and 15F, aged from 28 to 77 years with a mean of 53±14 (mean±sd) years) and 7 normal subjects (6M and IF, aged from 29 to 59 years with a mean of 41±13 years) were studied. The mean plasma aldosterone concentration in the diabetic patients was significantly lower than that in the normal subjects (137±62 vs 189±36 pmol/l, p<0.05). Seven of the 18 diabetic patients were hypoaldosteronemic. These 7 patients, however, showed normokalemia, except one with mild hyperpotassemia. The number of binding sites of [3H]aldosterone to mineralocorticoid receptor in the diabetic patients was significantly higher than that in the normal subjects (853±281 vs 488±109 sites/cell, p<0.05), but there was no significant difference in Kd of [3H]aldosterone binding to mineralocorticoid receptor between the diabetic patients and normal subjects (1.34±0.37 vs 0.99±0.61 nmol/l). In the diabetic patients, a significant negative correlation was observed (r=0.70, p<0.01) between plasma aldosterone concentration and the binding sites, but not between plasma aldosterone concentration and Kd. In the total subjects, including normal subjects and diabetic patients, a significant negative correlation was also found between plasma aldosterone concentration and binding sites (r=0.72, p<0.001). These results suggest that increased binding sites of mineralocorticoid receptor may help to prevent diabetic patients from being hyperkalemic.