Diuretic responses to water‐load in four strains of mice

Abstract

1. The kinetics of excretion of water, sodium and potassium following a stomach load of water, with and without an initial injection of vasopressin, are described in each of four strains of mice: RAP, CBA/FaCam, Peru and A/Cam. 2. In general there was a diuretic lag followed by an increase in the rate of excretion of water to a maximum, after which the rate of excretion fell again to near resting levels. The rate of excretion of sodium rose to an initial maximum which significantly preceded the maximum rate of water excretion. The rate of excretion of sodium then fell to a minimum at a time not significantly different from the time of maximum rate of water excretion. 3. The effect of an initial injection of vasopressin was to increase and to prolong the initial rise in rate of sodium excretion. The maximum rate of water excretion and the minimum sodium concentration were delayed, but the levels eventually reached were not significantly altered, by the vasopressin injection. 4. The strains of mice differed significantly in diuretic lag, maximum rate of diuresis, and 3 hr excretion of water and electrolytes. 5. The strains also differed significantly in the effects of vasopressin, both in increasing diuretic lag and in increasing sodium excretion. There was no correlation between the antidiuretic and natriuretic effects of vasopressin.