Abstract
The smallest dose of the selected substances which would produce histological changes in the kidneys of rabbits was first determined. Doses approximately one-half this amount were then injected daily intramuscularly and the effect upon the blood pressure studied. Uranium nitrate, lead acetate, phosphorus, ergot, viosterol, cholesterol, lecithin, putrescin, tyramine, arginine carbonate, asparagine, glutamic acid, histidine, tyrosine, tryptophane, succinic acid, aspartic acid, and guanidine carbonate were used. Of this entire group aspartic acid and guanidine alone produced progressive increase in systolic blood pressure.
The animals were kept in the laboratory for at least one week before blood pressures were taken. Then daily blood pressures were recorded for at least one week before the animals were used. The animals received the same diet of oats, greens, and carrots. The control animals were observed for the same length of time as treated ones. Only the systolic pressure was taken and the procedure of McGregor 1 used. The blood pressure was taken at first daily, and then 3 times weekly, the longer period being found sufficient for statistical purposes. The pressures for each week were averaged and the rise or fall recorded. Increases of 20 mm. of mercury or greater were considered as significant.
Fourteen animals injected with neutralized aspartic acid (doses varying between 20 and 250 mg. per kilo of body weight) all showed a rise in systolic blood pressure, the maximum rise being 25 mm. after 6 weeks and 73 mm. after 22 weeks. (See chart 1). The minimum dose of aspartic acid to produce an elevation of blood pressure was 40 mg. per kilo. Further increases of aspartic acid did not cause a more rapid or higher elevation of blood pressure. Blood urea and creatinin were within normal limits.
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