Abstract
There appears to be no report regarding the influence of dietary protein on biosynthesis of ascorbic acid in the rat. Prompted by a chance observation that rats receiving a high protein diet excreted relatively large amounts of ascorbic acid in urine, we investigated the influence of dietary protein on the Vit. C status of the rat. In the first instance, the effect of variations in dietary protein levels was examined.
Materials and methods. Adult male albino rats (Wistar strain) with body weights in the range 180-200 g were employed in all experiments. Animals were distributed according to the randomized block design for the various test treatments. Diets fed had the following composition: Protein (Polson's lactic casein)—according to choice; fat (refined peanut oil)—10%; vitaminized starch—1%; salt mixture‡—2%; and corn starch—to 100.
The vitaminized starch contained thiamine hydrochloride 40 mg, riboflavin 80 mg. niacin 100 mg. pyridoxine hydrochloride 40 mg, calcium pantothenate 100 mg and folic acid 5 mg per 100 g. The rats were given necessary amounts of diluted shark liver oil twice a week to provide the requirements of Yit. A and D.
Cages with wide mesh wire bottoms which were well covered with resistant paint were used to house the animals individually. Urine was collected in brown glass bottles containing 10% trichloracetic acid (TCA) over 3-day periods. Collecting funnels and bottoms of cages were rinsed with 10% TCA solution at least thrice a day during the collection period. Urine collections were made up to known volume and aliquots used for estimation of total Vit. C (ascorbic acid. dehydroascorbic acid and diketogulonic acid) according to the dinitrophenylhydrazine (DNPH) method of Roe and Keuther(1). The same procedure was employed for estimation of ascorbic acid in tissues and blood.
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