ENHANCEMENT OF PERITONEAL FLUID ABSORPTION BY DEHYDRATION, MERCAPTOMERIN AND VASOPRESSIN

¹ Department of Metabolism, Walter Reed Army Institute of Research, Washington, D.C.

The effects of dehydration, mercaptomerin (Thiomerin) and vasopressin on kinetics of transperitoneal fluid and solute absorption were compared in 40 dogs. Rate of absorption of intraperitoneally administered 0.9% saline was measured serially for 6 hr by an isotopic technique using radioiodinated serum albumin as a volume marker. Dehydration enhanced fluid absorption during the first hour, but hot between 2 and 6 hr after saline infusion. Dehydration did not alter solute absorption. Thiomerin administration increased absorption of water and solute, but only after a period of diuresis. These effects of Thiomerin were reversed when saline solution was given intravenously to replace urine volume. Thus, Thiomerin enhances peritoneal fluid and solute absorption indirectly through the hypovolemia which attends diuresis rather than through a direct action on the peritoneal membrane itself. Vasopressin administered intraperitoneally also increased fluid and solute absorption. Intravenously administered vasopressin had no effect. These findings suggest that vasopressin modified absorption through a direct action on the peritoneal membrane or its blood supply. Present results indicate that rate of peritoneal fluid and solute absorption depend upon an interaction among multiple forces. The relative importance of each varies with the time elapsing after intraperitoneal fluid administration.