The assay of hypertensin from the arterial blood of normotensive and hypertensive human beings.

Hypertensin has been assayed in the blood of patients with normal blood pressure and in those with essential hypertension in both the benign and malignant phases. 250 ml. samples of arterial blood were obtained, chemically purified, and concentrated to a volume of 1 ml. These extracts were then assayed in anesthetized rats. The concentrations of hypertensin in the blood of patients with the malignant phase of essential hypertension were found to be greatly increased. The concentrations of hypertensin found in patients with benign hypertension had a moderate degree of overlapping with those found in the normotensive group, but the mean concentration of hypertensin in the former group was twice that of the controls. Although these results are statistically significant, the amounts of hypertensin recovered in the benign group are so small that no conclusions can be drawn as to its effectiveness in producing vasoconstriction in these patients.