An Evaluation of Factors Affecting Survival of Choline-deficient Weanling Rats with Special Emphasis on Dietary Sodium

Abstract

Extensive death losses due to hemorrhagic kidney damage occur in weanling rats after they have been fed a choline-deficient diet for 7 to 10 days. We have investigated the effect of dietary factors other than choline content, and changes in several physiological functions on the survival of choline-deficient, male, weanling rats during this critical period. Special emphasis was given in these studies to alterations in the sodium content of the diets. A choline-deficient diet was supplemented with organic and inorganic salts, chelating agents, and diuretics. A sodium-deficient, choline-deficient diet was also studied. Feed intake, growth rate, urine volume, urinary mineral excretion patterns and plasma NPN levels were determined. Weanling rats receiving a choline-deficient diet were subjected to a physiological crisis on about the seventh experimental day caused by renal damage. Sixty-two per cent of rats with an initial weight above 75 g survived this crisis, whereas only 46% of the rats with an initial weight less than 75 g survived. The addition of 0.7% NaCl to a choline-deficient diet that contained adequate sodium for growth increased the survival of the heavier rats to 88%. Results of this diet with the lighter rats were variable. The NaCl diet was diuretic and caused an increase in the urinary excretion of Na, Ca and K. The addition of EDTA to the choline-deficient diet increased survival of the heavier rats to 75% and the lighter rats to 81%. EDTA depressed feed intake, urine volume, growth, and delayed the onset of high plasma NPN levels and kidney damage past 7 days. The sodium-deficient, choline-deficient diet also increased survival to 90%, apparently by depressing growth during the first 5 experimental days. None of the diets studied, except the choline-supplemented diet, completely protected rats from hemorrhagic kidney damage.