Target-organ interaction: Considerations of the effects of sodium and water retaining hormones on renal function

In this paper the characteristics of a membrane having properties similar to those of frog skin are considered in relation to renal function. Such a membrane, as discussed by H. H. Ussing and K. Zerahn (Acta. Physiol. Scand.,23, 110, 1951), is capable of acting as a sodium pump actively transferring sodium ions through the membrane. Water transfer is regarded as dependent upon osmotic and hydrostatic pressures and on the permeability of the membrane to water. It is shown that for a membrane having these properties the rate of transfer of sodium is a function of the rate of transfer of water andvice versa. In this case a change in, say, the flux of water across the membrane may lead to a similarly directed change in the sodium flux across the membrane. If the E.M.F. developed by the sodium pump is controlled by a sodium retaining hormone (SRH.) and the permeability of the membrane to water by antidiuretic hormone (ADH.), it follows that there is an interaction between the two hormones which is a property of the membrane upon which they act. It is suggested that the mechanism of action of the renal tubules with regard to sodium and water excretion may be not entirely dissimilar to that discussed for frog skin, and on this supposition the characteristics of the renal response to certain physiological stimuli are deduced and found to be in excellent agreement with observation. In particular, the excretion of a urine initially hypotonic in response to an isotonic saline infusion is explained as is also the inability of, physiological doses of, ADH to inhibit isotonic or hypertonic saline diuresis. Dr. Cole is in the Department of Medicine, and Mr. Meredith is in the Department of Electrical Engineering.