Effect of acute vascular fluid volume expansion on erythrocyte sodium transport in essential hypertension

Evidence exists that volume expansion is associated with the appearance of a circulating sodium transport inhibitor. We have evaluated intra-arterial blood pressure (BP), central venous pressure (CVP), plasma renin activity (PRA), intraerythrocyte sodium content, erythrocyte sodium influx and rate constant of sodium efflux in 10 untreated primary hypertensive men (WHO stages I and II). The investigations were done during baseline conditions and after rapid intravenous infusion of 1 litre of saline (0.9% NaCl solution) over 15-20 min. Volume expansion caused an increase in CVP by 6.0±0.5 cmH20 (p