Inherited defect in a Na+, K+ -co-transport system in erythrocytes from essential hypertensive patients

Abstract

The Na+ and K+ electrochemical gradients across cell membranes are believed to be maintained by the action of a Na+, K+-pump. In human erythrocytes this pump exchanges internal Na+ for external K+ in approximately a 1.5 ratio. Thus, when Na+-loaded/K+-depleted erythrocytes are incubated in physiological conditions they tend to recover their original low Na+/high K+ content. Surprisingly, in erythrocytes from healthy donors the net Na+ extrusion/K+ influx ratio exceeds the 1.5 ratio predicted for Na+, K+-pump-mediated fluxes whereas it is similar to this value in erythrocytes from essential hypertensive patients and some of their descendants. We now report that this difference is due to the presence of a Na+, K+-co-transport system in normal erythrocytes which extrudes both internal Na+ and K+ and is functionally deficient in erythrocytes of essential hypertensive patients and some of their descendants. No difference in passive Na+ permeability could be detected between normotoensive and hypertensive subjects.

Salt Sensitivity of Japanese from the Viewpoint of Gene Polymorphism

“…Multiple genetic and environmental factors determine one's blood pressure level, and "essential hypertension" is merely the upper end of the distribution (1). Subjects with essential hypertension are those who happen to inwith essential hypertension and in some of their normotensive relatives (3). The same defect is found in several strains of experimental animals bred for high susceptibility to saltinduced hypertension or spontaneous hypertension.…”

The effects of calcium on potassium transport in ferret red cells.

“…Ferret red cells thus provide an excellent system in which to examine factors which might control the activity of the co-transport system. Recent theories assign key roles to the cotransport system in the activation of secretion in epithelia (Petersen & Maruyama, 1984) and in the genesis of some types of essential hypertension (see, for instance, Garay, Dagher, Pernollet, Devynck & Meyer, 1980;Garay, Nazaret, Hannaert & Price, 1983). Alterations in intracellular ionized calcium concentration are central to these theories (see also Blaustein, Lang & James-Kracke, 1981).…”

Effects of drugs on sodium metabolism.

“…Recently interest in the red cell transport systems has been restimulated by the work of Meyer's group (Garay et al, 1980) (TC 199) containing 22Na (0.9 uCi/,ul). The rate constants are then determined for ouabain sensitive and ouabain insensitive sodium efflux.…”

“…This cell is easily obtained in multiple samples and has been much studied both in relation to ion content and ion flux (Canessa et al, 1980;Garay et al, 1980). In 1957 Skou described an enzyme found in the leg nerve of the shore crab which appeared to have an important relationship to active transport of sodium and later came to be known as sodium potassium ATPase.…”