Course of mercurial diuresis during Pitressin infusion in mild congestive heart failure

¹ Medical Division, Montefiore Hospital, New York City

In an attempt to assess the influence of diminished filtration rate on the renal response to a mercurial diuretic, with particular emphasis on anisosmotic (free) water reabsorption, six patients with mild congestive failure were given Mercaptomerin, 2 ml, i.v., while receiving a constant infusion of Pitressin 2 µ/kg/hr. During the control collection periods, the anisosmotic water reabsorption was less than that encountered previously in a group of normal subjects. With the onset of diuresis, free water reabsorption rose to the same levels as that of normal individuals and, thereafter, followed the same course. The changes observed are compatible with the hypothesis that free water reabsorption is limited by either of two factors, at low flows, the concentration gradient along the tubule and, at higher flows, the maximal ability of the anisosmotic segment to reabsorb water at a given level of hydration and antidiuretic activity.