Ouabain-binding and 86rubidium-uptake in lymphocytes of normal and borderline hypertensive subjects.

In borderline hypertensives cellular sodium concentration seems to be increased, indicating that cellular abnormalities are present in the early course of essential hypertension. In order to study the mechanisms underlying this finding the number of sodium/potassium pump sites and the cation pump activity were studied in lymphocytes of nine borderline hypertensives (27 (20-36) years) and nine controls (28 (20-36) years). Maximum 3H-ouabain binding and 86Rb-uptake were taken as measures of the number of pump sites and cation pump activity, respectively. The median number of sodium/potassium pump sites was 49.6 X 10(3) molecules/cell in the BH group compared to 32.4 X 10(3) in the control group (P less than 0.01). Median 90 min 86Rb-uptakes were 54.0 pmol/10(6) cells in BH subjects and 39.4 in controls (P less than 0.10). The increased number of sodium/potassium pump sites and the tendency to increased cation pump activity in lymphocytes of BH subjects in vitro may be interpreted as an adaptive change possibly induced by a circulating natriuretic substance.