Abstract
Previous work 1 has led us to conclude that mercurial diuretics act by diminishing tubular reabsorption, while administration of amino-phyllin produces an increase in the volume of the glomerular filtrate. Earlier work 2 suggested a high circulating blood volume in congestive heart failure, but there was no complete agreement as to the change following diuresis. Recent determinations 3 by a more satisfactory method 4 demonstrate a marked elevation of blood and plasma volume in patients with failure, and a decrease towards normal with the development of circulatory compensation. A similar decrease has been noted after the use of mercurial diuretics. 5
We have followed over 12 to 24 hours the changes in plasma volume, determined by the method of Gibson and Evelyn, 4 after the injection intravenously of one of the 3 types of diuretic drugs, salyrgan, aminophyllin, and digoxin. The urinary output has also been carefully followed, and the plasma volume correlated with the degree of diuresis. Data from typical experiments are recorded in Table I. It is to be emphasized that under the conditions of our experiments the plasma volume is influenced by fluid loss through the kidneys and fluid mobilization from the tissues. These factors exert an opposite effect, and their relative magnitude determines the blood volume.
When digoxin is injected in a dose of 2 mg there is first noted a slight increase in the plasma volume. This has never been great, 2nd the time of its appearance seems to depend on the attainment of the desired myocardial effect. As the rate of urinary flow accelerates, this increase disappears and is followed by a reduction, the amount of which is determined by the rate of diuresis.
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