Franz Volhard Lecture 1996. Sodium transport inhibitors and hypertension.

SODIUM EXCRETION IN HYPERTENSION: The concept that blood contains a sodium transport inhibitor with natriuretic and pressor properties emerged in the 1960's and 1970's from three separate lines of enquiry. The control of sodium excretion, in normal man and animals undergoing volume expansion, in uraemic man and animals, and thirdly the effect of cations on arteries from normal and hypertensive animals. Each of these studies led to the notion that the plasma contains a digitalis-like substance which increases vascular tone by raising intra-cellular calcium. Na-K,ATPase inhibitors were then found in increased quantities in the plasma in essential hypertension and experimental hypertension. As a result it was proposed that in essential hypertension a hereditary renal impairment to excrete the usual large amounts of sodium consumed by most populations increased the circulating concentration of this substance and thereby the arterial pressure. ENDOGENOUS OUABAIN: Substances spectrometrically identified to be plant ouabain have now been found in human plasma and bovine hypothalamus. Derivatization experiments have shown that the 'plant' ouabains in human plasma and bovine hypothalamus are the same substance but that they are different from true plant ouabain. The endogenous ouabain analogue may have direct pressor effects centrally and peripherally.