Humoral regulation of renal growth. Evidence for and against the presence of a circulating renotropic factor.

The stimuli for compensatory renal growth following a decrease in functioning renal mass have interested a number of investigators. The existence of a humoral incitor and/or regulator of renal growth, renotropin, has been postulated; and three types of experiments have been performed to determine its existence. These include parabiotic, in vivo, and in vitro assays. In general, the three different methodologies support the existence of a renotropic factor (or factors) but further investigations are needed to clarify its precise roles in compensatory renal growth.