9522534 Simpson When one kidney or part of a kidney is surgically removed or becomes dysfunctional, the mass of the remaining kidney increases in a compensatory manner to maintain normal or near normal renal function. The processes that regulate the compensatory changes are not understood. In this proposal, Dr. Simpson puts forth the hypothesis that compensatory growth is the result of the inhibition of a organ-specific factor in the blood that normally suppresses tissue growth. Thus, when this factor is inhibited, specific tissues begin to proliferate. The growth is typified by an increased rate of cell division. He suggests that the suppressant material is produced by the organ (kidney in this case) itself to prevent over growth. Removal or loss of an organ reduces the plasma concentration of the suppressant and consequently permits cell growth. He will test this hypothesis by infusing plasma from a normal animal into one where two thirds of the kidney has been removed. This should prevent cell growth. Cell growth (division) will be tracked by DNA synthesis (incorporation of 3H-thymidine) 24 hours after the infusion of donor plasma. These experiments have the potential of providing valuable insights into normal and abnormal cell growth an regulation. ***
