INTEGRATED ANALYSIS OF ERYTHROCYTE NA+ H+ ANTIPORT ACTIVITY AND LEFT-VENTRICULAR MYOCARDIAL-FUNCTION IN TYPE-I INSULIN-DEPENDENT DIABETES-MELLITUS/

Membrane NA(+)/H+ exchanger regulates cell pH, volume, and growth. Abn ormal activities have been reported in essential hypertension and type I insulin-dependent diabetes mellitus (IDDM). The aim of this study w as to analyze the relationship between erythrocyte NA(+)/H+ antiport a ctivity and myocardial anatomical and functional parameters in normote nsive type I insulin-dependent diabetic patients. We evaluated 26 insu lin-dependent diabetic patients (20 normo- and 6 microalbuminuric) and 17 age- and sex-matched healthy controls. Plasma and urine analytes a s well as erythrocyte NA(+)/H+ antiport rate were measured. M-Mode- an d 2D echocardiograms with Doppler analysis were performed in all subje cts. Diabetic people, both normo- and microalbuminuric, had a Na+/H+ a ntiport activity significantly higher than control subjects (p < 0.01) . All echocardiographic parameters relative to left ventricular volume , cardiac mass and systolic function overlapped in the study groups. O f Doppler indexes, evaluating the left ventricular diastolic filling, the late peak flow velocity (peak A) was significantly higher in diabe tic patients (p < 0.01). EIA ratio was heightened in the control group compared to diabetics, as a whole as well separately considered (p < 0.01). Antiport significantly correlated with PWTh, STh, EIA, UAER, se rum sodium, and gender (p < 0.0001). The linear and significant correl ation found between Na+/H+ exchange and some cardiac indexes suggest t he increased Na+/H+ antiport activity as possible predictive risk fact or for the development of diabetic cardiomyopathy.