Sodium-potassium cotransport in hypertension and hypotension

Furosemide-sensitive Na-K cotransport was measured as zerotrans efflux of each ion from fresh or Na loaded erythrocytes in normotensives (n=34), essential (n=41) or secondary (n=12) hypertensives and essential (n=17) or secondary (n=5) hypotensives.The stoichiometry of Na and K efflux was 0.9: 1 in fresh cells and 1: 1 in cells loaded with sufficient Na to give near the maximum velocity (Vmax) in a combined analysis.There was a tendency toward a negative correlation between the Vmax of Na efflux and serum total cholesterol (p=0.09) in the whole and it was significant in normotensives (r=-0.60). Vmax of Na efflux also negatively correlated to age (p<0.01). After adjustment for age and total cholesterol level, essential hypertensives had a significantly (p<0.01) higher mean Vmax of Na efflux (0.657±0.029mM/l cells/hr) than normotensives (0.388±0.045), while essential hypotensives had a lower value (0.212±0.047) (p<0.01).Na efflux from fresh cells adjusted for internal Na content was higher in essential hypertensives (0.173±0.018) than in normotensives (0.107±0.026) (p<0.05).Thus, elevated cotransport was linked to essential hypertension and reduced cotransport to hypotension. Whether it is a cause or a result remains to be further investigated.