CARDIOVASCULAR REMODELING AND RED-BLOOD-CELL LI+ NA+ COUNTERTRANSPORTIN PATIENTS WITH TYPE-1 DIABETES AND ESSENTIAL-HYPERTENSION/

Patients with type 1 (insulin-dependent) diabetes may develop a specif ic cardiac disease characterized by functional and structural abnormal ities. The pathogenesis of the cardiac disease is poorly understood bu t cardiac and renal complications may coexist. Patients with overt dia betic nephropathy have increased red cell Li+/Na+ countertransport (CT ), which reflects abnormal kinetic properties of the red cell membrane Na+/H+ exchange. Since the activation of Na+/H+ exchange has a key ro le in cell proliferation and cell growth, as well as in the regulation of cell sodium and cell pH and in the renal reabsorption of Na+ and b icarbonate, we have looked for relationships between red cell Li+/NaCT, Na+/H+ exchange and cardiovascular remodeling in patients with typ e 1 diabetes, essential hypertension and idiopathic familiar cardiomyo pathy. In type 1 diabetes the maximal velocity of Li+/Na+ CT is positi vely correlated with interventricular septum thickness and the left ve ntricular wall to lumen ratio. Similar results were obtained in patien ts with essential hypertension. In these ,patients an increased Li+/Na + CT is also associated with severe and drug-resistant hypertension an d with significant vascular remodelling, estimated by the minimal post -ischaemic vascular resistance in the calf. Finally, Li+/Na+ CT is neg atively correlated with diastolic relaxation of the left ventricle in familiar hypertrophic cardiomyopathy. From these data it appears that wide-spread abnormal kinetic properties of Na+/H+ exchange, estimated by increased red cell Li+/Na+ CT, may have epistatic effects on the pa thogenesis of cardiac complications of type 1 diabetes and essential h ypertension.