Cause of the continuous rise in plasma renin concentration after removal of manipulated submaxillary glands in nephrectomized mice.

After gentle manipulation with subsequent removal of the submaxillary glands in nephrectomized mice there is a vast increase in the concentrations of high molecular weight renin ("prorenin"?) as well active renin in plasma. The increase in active renin is continuous even after removal of glands as well as kidneys. Using in vitro incubation and replacement transfusion experiments, the continuous rise was found not to be due to activation of the high molecular weight renin. The continous increase could instead be shown to be due to a rapid transfer of submaxillary lymph and (or) interstitial fluid to the surrounding tissues, with a subsequent slower release from these tissues to the blood. Continued release of renin from extra-submaxillary tissue-depots is probably also the cause of the continuance of the high plasma renin concentrations for several hours after the removal of the manipulated glands, which contrast with the much more rapid decline in the concentration after injection of extracts of submaxillary glands as well as after injection of pure submaxillary renin.