The Effect of Sulphonamides and of Cooking or Grinding the Diet on the Excretion of Vitamins of the B Complex by the Refected Rat

Abstract

Refection in rats was first recognized by Fridericia (1926), who described the condition as 'a transmissible change in the intestinal content, enabling rats to grow and thrive without B-vitamin in the food'. The existence of refection has been confirmed by later workers (cf. review by Kon, 1945), but the full mechanism of establishing and maintaining the refected state has not yet been satisfactorily explained.It is now known that the intestinal flora of rats, and indeed of most animals, synthesizes all the well-characterized vitamins of the B complex. The contribution of this microbial synthesis to the vitamin requirements of rats on normal diets is relatively small, but refected rats are evidently able to derive the whole of their B vitamins from the products of such synthesis. Thus either the total amount of vitamins synthesized must be greater in the refected than in the normal rat or the efficiency of utilization must be higher or, more probably, both. Kon, Kon & Mattick (1938) suggested that the presence of undigested starch in the caecum of the refected rat, along with the requisite starch-splitting enzymes led to a vigorous fermentation and a resulting acid pH that created conditions favourable for both vitamin synthesis and absorption.During recent years the effect of sulphonamides on the synthetic activities of intestinal micro-organisms has been extensively studied, and muchvaluable information 1946), who found that sulphonamides depressed the growth rate of the rats and their faecal excretion of both vitamins. Untreated refected rats excreted no measurable amounts of thiamine in the urine, whereas their urinary excretion of riboflavin was comparable with that of stock rats. Administration of sulphonamides caused a marked depression in this excretion. It was concluded from these experiments that thiamine is probably the limiting factor in refection, and that the bacterial flora of the refected rat synthesizes riboflavin in excess of requirements. In further work a more detailed study was made of the excretion by the refected rat of several members of the vitamin B complex and of the effect thereon of sulphonamides and of cooking or grinding the diet. EXPERIMENTAL GeneralThe experiments were done with two batches of rats. The first series of collections was made from the first of these batches in 1947, and the second series of collections from the second batch in 1949. The urine, faeces and caecal contents of the groups of rats were analysed for seven vitamins of the B complex: thiamine, riboflavin, nicotinic acid (and in urine N-methylnicotinamide), pantothenic acid, biotin, folic acid and vitamin B,. After the second series of collections the livers of the rats were also analysed for these vitamins. DietsThe first batch of rats received one of the following four diets: ( that the ability of starch to support refection would be destroyed on milling in the same way as on gelatinizing the starch by cooking. Management of ratsMale and female rats from the stock colony were placed at weaning on the refe...