ERYTHROCYTE NA-H+ EXCHANGER AND NA+-LI+ COUNTERTRANSPORT ACTIVITY IN PRIMARY ALDOSTERONISM()

Several authors have described increased Na-H exchanger activity in es sential hypertension but no data are available in secondary forms of h ypertension such as primary aldosteronism. We measured Na-H exchanger kinetics together with Na-Li countertransport V-max in the erythrocyte s of eight patients with primary aldosteronism and in 15 normotensive control subjects. Plasma aldosterone, plasma renin and plasma potassiu m were also evaluated. Na-H exchanger V-max appear to be increased in patients with primary aldosteronism and Hill's n, an index of co-opera tivity amongst intracellular proton binding sites, was significantly l ower in patients than in controls. No statistically significant differ ences were found between affinity for intracellular protons (K50%) and for Na-Li countertransport V-max between the two groups studied. We w ere unable to find any correlations between Na-H exchanger V-max and N a-Li countertransport V-max in the two groups considered as a whole. F rom the-present data Na-H exchanger overactivity would not appear to b e a specific feature of essential hypertension but seems to be charact eristic in patients with primary aldosteronism.