Renal inhibition of pressor responses to drugs.

FIFTY-FIVE years ago Tigerstedt and Bergman found the pressor response to intravenously injected renin increased after bilateral nephrectomy; more recently, Page and Helmer showed similar augmentation of response to injection of angiotonin, the reaction product of renin and substrate. Consistent with an apparent inhibitory influence of functioning renal tissue on responses to injected renin and angiotonin are studies which show that presence of normal kidney tissue reduces the severity of experimental renal hypertension and protects against the acute vascular lesions elicited by injection of renin-containing kidney extracts. The nature and mechanism of action of this renal inhibitory or protective influence are not known. It is known, however, that certain kidney extracts are effective in the treatment of experimental renal and clinical essential hypertension' "•; the efficacy of these extracts might depend upon the presence in them of a substance inhibitory to renin and angiotonin. Should such a substance occur in nature, its identification and preparation would be of clinical importance. But before confidently postulating its existence and again undertaking a search for it, it is prudent to determine whether or not the renal inhibitory and/or protective influence depends upon other identifiable mechanisms, to characterize its action further, and to determine its relationship to excretory renal function. These were the purposes of this study.