A classification of essential hypertensive patients according to the erythrocyte Na transport abnormalities: an application for monitoring the antihypertensive response to cicletanide.

We have studied the kinetic properties of the interaction of internal Na with four different Na transport pathways (ouabain-sensitive Na, K pump, bumetanide-sensitive Na,K cotransport, Li:Na countertransport and passive Na permeability) in erythrocytes from 197 essential hypertensive patients. This study permitted us to classify 168 of the 197 hypertensives studied into the following groups: Pump - hypertensives-six patients showing low pump affinity for internal Na and high maximal pump rate; Co - hypertensives -95 patients characterized by low cotransport affinity for internal Na and low or normal maximal outward cotransport rate. Counter + hypertensives - 35 patients characterized by low countertransport affinity for internal Na and high maximal countertransport rate; and Leak + hypertensives - 32 patients showing increased passive Na permeability. Having studied the apparent affinity of the Na,K cotransport system for external K we divided the co - hypertensives into three subgroups (symmetric, asymmetric or antisymmetric) according to the presence of low, normal or high K affinity. Forty-five hypertensive patients were submitted to antihypertensive treatment with a new diuretic and antihypertensive drug, cicletanide. Preliminary results indicate that one of the factors involved in the antihypertensive efficiency of the compound is the subgroup to which the hypertensive belongs.