Renal glutaminase activities in vitamin B6-deficient rats.

Glutamine has been implicated in the functioning of the central nervous system (l), in muscle metabolism (a), in transamination (3), in detoxification (4), and as a precursor of urinary ammonia (5). An excellent review of these and other possible r&es of glutamine in metabolism has been presented by Archibald (6). It would seem that glutamine acts as a mobile reserve of ammonia and glutamic acid in the body and would therefore be expected to effect a number of physiological functions. In this laboratory, a lowered plasma glutamine level has been found consistently in rats deprived of vitamin Bg and given deoxypyridoxine for a period of approximately 21 days (7-lo), but this lowering has not been observed in pair-fed controls. Simple deprivation of the vitamin for a period of 20 days did not elicit this lowering in the absence of deoxypyridoxine (11). A less marked but relatively consistent observation has been an elevated level of plasma glutamic acid in vitamin Be-deficient rats (7-10). These findings suggested the possibility of an alteration in renal glutaminase activity consequent to vitamin Be deficiency in the rat. Decreased levels of plasma glutamine in vitamin Be-deficient rats given deoxypyridoxine, but not in those simply deprived of the vitamin, might be attributable to differences in the degree of deficiency, since deoxypyridoxine has been shown to hasten the onset of external deficiency signs (12), or to an effect of deoxypyridoxine separate from antivitamin action. To investigate these possibilities, renal glutaminase activities have been measured in vitamin Bs-deprived and pair-fed control rats with and without provision of dietary deoxypyridoxine. Renal glutaminase activities were also measured in thiamine-deficient rats in order to investigate one other vitamin deficiency.