Impaired insulin-mediated erythrocyte magnesium accumulation is correlated to impaired insulin-mediated glucose diposal in aged non-diabetic obese patients.
Basal erythrocyte magnesium levels were significantly lower in obese than lean subjects. In vitro incubation in the presence of 100 mU/l insulin significantly increased magnesium erythrocyte levels in both groups of subjects. However, even in the presence of 100 mU/l, the erythrocyte magnesium content of obese patients was lower than that of control subjects. The in vitro dose-response curve of the effect of insulin on magnesium erythrocyte accumulation was shifted to the right when the red cells of obese were used, with a highly significant reduction of the maximal effect. Such reduction of the maximal effect of insulin suggests that the impairment of insulin-induced erythrocyte magnesium accumulation observed in obese patients results essentially from a post-receptor defect. In obese patients, net increase in erythrocyte magnesium levels (calculated as the difference between basal and 100 mU/l insulin-induced erythrocyte magnesium levels) was negatively correlated with basal plasma insulin levels (r = 0.79 p less than 0.01), and with body mass index (r = 0.81 p less than 0.01) while it was positively correlated with the glucose disappearance rate after glucose load (r = 0.67 p less than 0.05) and glucose metabolic clearance rate (r = 0.71 p less than 0.01). These results demonstrate that insulin-induced erythrocyte magnesium accumulation is impaired in patients with obesity and that such defect is correlated to impaired -- mediated glucosal disposal in the patients.
Paolisso
G
G
Instituto di Gerontologia e Geriatria, 1st Medical School, University of Naples, Italy.
Pizza
G
G
De Riu
S
S
Marrazzo
G
G
Sgambato
S
S
Varricchio
M
M
D'Onofrio
F
F
D000368:Aged; D000375:Aging / Q000097:blood*; D001786:Blood Glucose / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D008274:Magnesium / Q000097:blood*; D008297:Male; D008657:Metabolic Clearance Rate; D009765:Obesity / Q000097:blood*
D001786:Blood Glucose; D007328:Insulin; D008274:Magnesium