Cellular sodium membrane transport and cardiovascular risk factors in non—Insulin-dependent diabetes mellitus

Associations have been described between cardiovascular risk factors and abnormalities of both sodium-lithium countertransport (SLC) and sodium-hydrogen ion exchange in subjects with insulin-dependent diabetes mellitus. The data in subjects with non-insulin-dependent diabetes mellitus (NIDDM) are few and more conflicting. This investigation examines erythrocyte SLC rates and platelet sodium-hydrogen ion-exchange kinetics and their relationship to cardiovascular risk factors in 45 nondiabetic and 35 NIDDM white men. The two groups did not differ significantly in erythrocyte SLC or platelet buffering capacity, sodium-hydrogen ion-exchange maximal rate (Vmax), or K m for extracellular sodium. Within the whole group, controlling for the presence of diabetes, SLC correlated weakly with triglyceride concentration ( r = .23, P = .05), but not with urinary albumin excretion rate (AER), systolic or diastolic blood pressure, body mass index (BMI), or concentrations of glucose, insulin, or total or high-density lipoprotein (HDL) cholesterol. Platelet sodium-hydrogen exchange was not significantly related to any cardiovascular risk factor studied. In conclusion, (1) SLC activity was not increased in NIDDM subjects; (2) SLC rates correlated weakly with serum triglyceride concentrations; (3) platelet sodium-hydrogen exchange Vmax and K m for extracellular sodium and platelet buffering capacity did not differ between diabetic and nondiabetic groups; and (4) there was no significant relationship between platelet Na + H +-exchange kinetics and any of the cardiovascular risk factors studied.