Reduction of increased sensitivity to renin by cross circulation

¹ Research Laboratories, Pharmaceutical Department, CIBA Limited, Basle, Switzerland

Cross circulation between pairs of rats was established in order to modify the humoral environment for pressor action of injected renin. Blood exchange with normal rats led to a definite diminution of the increased sensitivity to renin usually seen in the nephrectomized or cortexone-treated animal. The humoral factor reducing renin hypersensitivity is rather stable and exerts its influence not only during, but even after, the duration of cross circulation. It is suggested that normal plasma contains a humoral substance of unknown, possibly renal, origin capable of either antagonizing or inactivating renin. This substance may be renin itself, a factor formed under its influence, or a principle produced by the kidney simultaneously with renin. In animals made hypertensive by an overdose of cortexone and salt, the increased and protracted response to exogenous renin is partly determined by an alteration of the cardiovascular system.