Ouabain-Resistant, Frusemide-Sensitive Sodium Efflux in Human Lymphocytes: A Comparison of Normotensive and Hypertensive Subjects

1. Peripheral blood lymphocytes were isolated at room temperature in a low sodium medium in 17 normotensive control subjects (NC) and 13 patients with essential hypertension (EHP). 2. Lymphocyte sodium content was not significantly different between NC and EHP (3.1 ± 0.5, n = 11, and 3.6 ± 0.5, n = 10, respectively; means ± sem). 3. The effect of frusemide on the ouabain-resistant rate constant of sodium efflux ( K Na o ) from these lymphocytes into a sodium-free medium was measured. 4. The frusemide-sensitive efflux rate constant was 75 ± 5 μs ( n = 17) in controls and significantly lower in EHP (32 ± 7 μs, n = 13, P 5. In human lymphocytes there is a ouabain-resistant, frusemide-sensitive fraction of sodium efflux into a sodium-free medium; this fraction may be reasonably attributed to a sodium-potassium cotransport system. This sodium transport pathway seems to be reduced in lymphocytes from EHP.