Hydroxyethyl Starch Effects on Rat Warm Renal Ischemia

Abstract

Fractions of hydroxyethyl starch (HES), 100,000-1,000,000 daltons, have been shown to reduce increased permeability changes in postcapillary venules associated with ischemia-reperfusion injury in canine myocardium and rat skel etal muscle. The authors studied the effect of intravenous administration of two fractions of the biodegradable HES, Fm (100,000-300,000 daltons) and FLm (300,000-1,000,000 daltons), in the prevention of acute renal failure in a rat warm renal ischemia model. A series of renal artery cross-clamp times was used to determine the threshold for irreversible damage (thirty minutes). After thirty minutes of warm renal ischemia, 2.5 cc of 6 % Fm or FLm solution, 5% human serum albumin, or 9% normal saline was administered. The effect of the solutions was evaluated by four criteria: (1) forty-eight hours' serum BUN/creatinine, (2) forty-eight hours' urine output, (3) percent of water content in the kidney, and (4) a histopathologic grading. There were no differences among the animals in any of the four groups in renal function at forty-eight hours, percent of water content of the kidneys, urine output, and extent of medullary and cortical injury. The authors attribute the lack of protective effect by the HES macromolecules to intrinsic properties of the kidney such as the extensive endothelial cell surface area of the well-vascularized kidney and the hypersensitivity of the kidney to hypoxic injury.