OBSERVATIONS CONCERNING THE PRESSOR SUBSTANCE PRESENT IN THE ISCHEMIC KIDNEY BLOOD OF THE DOG

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Abstract
In previous work the presence of a pressor substance in the venous blood of either an isolated perfused kidney or of the intact kidney of the dog was reported. This substance could be detected in the blood leaving the partially ischemic kidney within 15 mins. after the initiation of the partial ischemia. Its pressor quality per ccm. at this time was as strong as that found in blood obtained after a much longer period of partial ischemia, indicating that the production of this substance was not necessarily dependent upon progressive autolysis or destruction of the kidney. The ischemic kidney blood had a pressor effect which differed from that of renin in that its action was immediate and of moderate duration. Further, animals made tachyphylactic to the introduction of ischemic kidney blood still reacted to the inj. of renin. These differences showed that the pressor quality of the ischemic kidney blood was not due to the presence of renin alone. The renal pressor substance was nullified by the action of heat on the plasma containing it. It was also ineffective when injected into a dog via the renal artery supplying a normal kidney. The renal pressor substance could not be removed from ischemic blood plasma by prolonged dialysis of the latter nor was it ineffective when given to cocainized dogs. Since this ischemic kidney blood contained a pressor substance that Was not exactly similar to renin in its physiological actions and differed somewhat from "angiotonin" ("hypertensin") in some of its chemical properties, the substance was apparently not identical to either of them.