A crucial role of humoral factors in the pathogenesis of
primary hypertension is discussed. In 1982 Hamlyn et al demonstrated the presence of a
Na+, K(+)-ATPase inhibitor in the plasma of essential hypertensives and showed a significant correlation of the Na+, K(+)-
ATPase inhibition with the blood pressure. In this study we examined whether an
Na+, K(+)-ATPase inhibitor could be found in the blood of essential hypertensives as compared to patients with secondary
hypertension (renal hypertension, renal artery
stenosis,
pheochromocytoma). Second, the possible correlation between an inhibition of Na+, K(+)-
ATPase and the intracellular
electrolyte composition was examined. The results demonstrate a similar reduction of Na+, K(+)-
ATPase inhibition in both essential hypertensives and secondary hypertensives as compared to normotensive controls. Further, the intracellular
electrolyte composition (Na+, Na; K+, Ca) does not show a significant correlation to the degree of Na+, K(+)-
ATPase inhibition, whereas a significant correlation between the degree of Na+, K(+)-
ATPase inhibition and intracellular Cl- concentration could be demonstrated. The present study shows that an endogenous
Na+, K(+)-ATPase inhibitor is also present in secondary forms of
hypertension, thus implying that a specific role in the pathogenesis of
primary hypertension for an Na+, K(+)-inhibitor is unlikely.