Genetic control of renin activity in the submaxillary gland of the mouse

Administration of androgen to female mice is known to increase the level of several proteins in the submaxillary gland, including nerve growth factor, epidermal growth factor, esteroproteolytic activity and renin. In the present study, renin activity has been assessed in extracts of submaxillary gland of female mice from two inbred strains (SWR/J and C57BL/10J), from F₁ and F₂ hybrids, and from backcrosses between F₁ and parental strains. In both uninduced and induced mice, renin activity of submaxillary gland was more than 100-fold greater in SWR/J than in C57BL/10J mice as measured by either an enzymatic assay or an immunodiffusion method. This difference was not due to differences in plasma testosterone levels between the strains, and the enzymes from the two strains had similar pH optima, substrate specificities, heat stabilities, and apparent Michaelis constants. In the submaxillary gland the difference was relatively specific for renin because increases in esteroproteolytic activity, nerve growth factor and epidermal growth factor after androgen treatment appeared to be similar in both strains. Studies with the various hybrids indicate that the difference in renin activity between the two strains is apparently due to a single regulatory gene.