EFFECT OF PYRIDOXINE AND TRYPTOPHAN, ALONE AND COMBINED, ON THE DEVELOPMENT OF DEOXYCORTICOSTERONE ACETATE-INDUCED HYPERTENSION IN RATS

Chronic dietary administration of pyridoxine HCl (300 mg/kg/day), L-tr yptophan (1.26 g/kg/day), or a combination of the two can attenuate th e elevation of systolic blood pressure in DOCA-salt-treated rats. With these treatments, the characteristic increase in the weight of the he art accompanying chronic administration of DOCA (786 mu g/kg/day) was also attenuated. Thus, both tryptophan and pyridoxine possess antihype rtensive properties, and the combination of the two appeared to provid e greater protection than either alone. The results are consistent wit h the possibility that pyridoxine, an important cofactor in the metabo lic pathways for tryptophan, may facilitate the conversion of tryptoph an to antihypertensive compounds. Additional studies will be required to determine which of the metabolites of tryptophan possess antihypert ensive properties. Pyridoxal phosphate, one of the metabolites of pyri doxine, was also administered chronically in the diet (1.0 and 2.0% by weight) to rats whose blood pressures were elevated by administration of DOCA. The results of this study suggest that pyridoxal phosphate c an also lower the blood pressure of rats with established hypertension , Thus, these studies reveal that pyridoxine, pyridoxal phosphate and tryptophan are potential antihypertensive agents.