Failure to Demonstrate Pressor Properties in Extracts of Blood from Hypertensives

The theory that hypertension may be due to the accumulation of a humoral pressor substance or substances of renal origin has been supported by the finding of increased concentrations of pressor material in kidneys from patients with various hypertensive diseases 1 and from dogs with experimental renal hypertension, 1 2 3 Against this hypothesis is the failure to find increased pressor properties in the blood of subjects with hypertension. 4 Recent chemical studies 5 indicated that the pressor principle in rabbits'kidneys is related to the globulins. This work suggested the possibility of concentrating the hypothetical pressor substance in blood by similar chemical procedures. The present report is concerned with the vasomotor properties of extracts of human and of dog's blood containing protein fractions prepared in the following way.

Approximately 100 cc of freshly drawn blood was defibrinated and centrifuged. The serum was drawn off and half saturated with ammonium sulfate, and the resulting precipitate dialyzed against tap water until free of sulphate. The dialysate was then dried in a Florsdorf-Mudd apparatus 6 and taken up in a small volume of saline. The final solution was tested by intravenous injection into small unanesthetized dogs with Van Leersum (carotid) loops, and the effect on the blood pressure noted.

Observations were made on the blood of 5 patients with persistent hypertension, and 3 dogs with hypertension due to renal ischemia. 7 In no instance was a well-defined pressor response noted.

The failure to find the renal pressor material in the blood stream may be due to a number of possible causes, such as inefficient extraction, insufficient amount of the pressor substance in the blood stream, or differences between the chemical properties of renal pressor substance in man and rabbits. It is also possible that ultimately the pressor substance may prove to have no relation to hypertension.