Herbert Nowak

Automatic determination of xanthurenic acid

Abstract An automatic method is described for the colorimetric determination of xanthurenic acid in urine which proved effective in an extensive series of analyses. This procedure is definitely superior to the conventional method of colorimetric determination with regard to both accuracy and working speed. Within the concentration range 5–250 mg 100 ml this automatic method works with a mean deviation of the individual values of 5%. Reproduction at a working speed of 30 samples per hour—which has proved practical in analysis of biological material—may, at a standard deviation of not more than 1.12%, be considered very good. The recording limit for xanthurenic acid is below 1 mg 100 ml .

NEUROCHEMICAL CHARACTERIZATION OF PYROXAMIDIN, A NEW ANTIHYPERTENSIVE DRUG

In contrast to other guanidine derivatives, pyroxamidin (EMD 21192) showed remarkably selective effects on the adrenal medulla whose adrenaline (A) content could be depleted almost completely at doses which reduced heart and vas deferens noradrenaline (NA) levels only moderately. The results presented indicate that pyroxamidin lowers blood pressure by a complex mechanism, involving possibly also inhibition of adrenal catecholamine (CA) output which might be of special relevance in controlling stress-induced increases in blood pressure.