Abstract
Conclusions
1. One lot of a vitamin A concentrate dissolved in sesame oil produced striking reductions in the blood pressures of renal hypertensive dogs when administered by mouth in a dosage of 200,000 units daily for 3 months followed by 400,000 units daily for 3 months.
2. Second and third lots of the concentrate dissolved in sesame oil and fish liver oil respectively, a purified vitamin A alcohol in sesame oil, and a fourth lot of the concentrate dissolved in fish liver oil and subjected to heat inactivation of the vitamin A, as well as sesame oil, were all without antihypertensive effect. Likewise the second lot of the concentrate showed no prophylactic effect in experimental renal hypertension.
3. No toxic effects were observed in the dogs.
4. Obviously the antihypertensive effect of the first lot of the concentrate was not due to vitamin A but to some unknown constituent not present in the second and third lots.
5. Since this antihypertensive substance was effective by mouth and apparently in small amounts, further work leading to its reproduction and identification is highly desirable.
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