Distribution and disappearance rate of submaxillary renin.

Highly purified submaxillary renin (SR) labeled with 125I was injected intravascularly into adult male mice following removal of submaxillary glands and kidneys, and the disappearance of this labeled SR from the circulating vascular volume was studied on the basis of a two compartment system. There was a fast and a slow component to the disappearance curves. Mean half-times of the fast and slow component were 12.4 +/- 0.4 min and 86 +/- 3 min in sialoadenectomized mice, while in mice whose submaxillary glands and kidneys were removed the half-times were 14.7 +/- 0.4 min and 108 +/- 7 min, respectively. The uptake of radioactivity by various organs of the mouse was also measured. Accumulation of radioactivity occurred in the kidneys and liver. Only trace amounts of radioactivity were found in the other organs. The findings suggest that the fast component of the disappearance curve was probably due to equilibration of the injected labeled SR in the circulation. However, the fast component may be related to some extent to the rapid uptake of labeled SR by the kidneys. The half-time of the slow component may represent the true halflife of SR in mice, since a significant reciprocal relationship between the half-times of the slow component and metabolic rate constant k10 was observed both in sialoadenectomized mice and in nephrectomized-sialoadenectomized mice.