TRANSMEMBRANE SODIUM-TRANSPORT KINETICS I N ESSENTIAL-HYPERTENSION - ITS RELATION WITH CARDIOVASCULAR RISK PARAMETERS

BACKGROUND: To characterize the possible existence of kinetic anomalie s of four erythrocyte membrane sodium transport systems in a group of essential hypertensive patients, and to study the clinical and biochem ical profile of those with anomalies. METHODS: We studied 33 essential hypertensive patients and 33 normotensive controls. The kinetics (max imal rate and apparent dissociation constant for internal sodium) of N a+-K+ pump, Na+-K+-Cl- cotransport and Na+Li+ countertransport was cal culated after a sodium loading procedure, according to the methods of Garay; the passive Na+ permeability was also determined. RESULTS: The studied kinetic parameters were not significantly different in both gr oups. Nevertheless, we found a group of hypertensive patients with som e transport abnormalities: increased intracellular sodium (9.1%), acce lerated Na+ pasive permeability (9.1%), lower activity of the Na+-K+ p ump (7.1%) and the Na+-K+-Cl- cotransport (4%) and an increased maxima l rate of the Na+Li+ countertransport (11.8%). Na+Li+ countertransport activity was statistically related to plasma levels of urea, creatini ne, glucose and LDL-cholesterol, and the activity of the Na+-K+-Cl- co transport was related to plasma uric acid. The hypertensive patients w ith sodium transport anomalies showed higher body mass index, uric aci d plasma levels and atherogenic index than those without these kind of anomalies, and they also showed lowered HDL-cholesterol plasma levels . CONCLUSIONS: A small group of essential hypertensive patients (aroun d 31%) show kinetic alterations of sodium transport systems. There is a relation between Na+-Li+ countertransport activity and some cardiova scular risk parameters. Hypertensive patients with transport anomalies are a group with an increased cardiovascular risk.