Effect of some organic acid salts of tris(hydroxymethyl)aminomethane in the incubation step on plasma renin activity.

The tris(hydroxymethyl)aminomethane salts of the organic acids acetylsalicylic, phenoxyacetic, salicylic, benzoic, acetic, and maleic were used to buffer the pH of plasma between 7.4 and 7.7 in a 1 h incubation step of the procedure for the determination of plasma renin activity. When compared to the plasma renin activity determined with tris(hydroxymethyl)aminomethane hydrochloride or with no buffer, it was found that all of the tris(hydroxymethyl)aminomethane salts of the organic acids studied produced a statistically significant increase in plasma renin activity except the salt of acetic acid when compared to tris(hydroxymethyl)aminomethane hydrochloride. In comparison to tris(hydroxymethyl)aminomethane hydrochloride and unbuffered plasma the organic acid salts and their mean percent difference in plasma renin activity are as follows: tris(hydroxymethyl)aminomethane phenoxyacetate (101%, 105%); tris(hydroxymethyl)aminomethane acetylsalicylate (79%, 115%); tris(hydroxymethyl)aminomethane benzoate (70%, 107%); tris(hydroxymethyl)aminomethane salicylate (64%, 70%); tris(hydroxymethyl)aminomethane maleate (32%, 60%); and tris(hydroxymethyl)aminomethane acetate (--1.6%, 43%).