EXPRESSION OF ADENYLYL-CYCLASE MESSENGER-RNAS IN THE ADULT, IN DEVELOPING, AND IN THE BRATTLEBORO RAT-KIDNEY

The activity and expression of adenylyl cyclases (AC) were examined in the adult rat renal cortex and medulla. Northern blot analysis and in situ hybridization demonstrated that AC-6 was the predominant isoform in the adult rat kidney, whereas AC-4, -5, and -9 had a lower express ion. AC-4 expression was higher in the cortex, and AC-5 and AC-6 were higher in the medulla. AC-9 expression was at the same level in both r egions. AC activity was high in the fetus and declined in the adult. A t all stages, AC activity was sensitive to parathyroid hormone, wherea s no stimulation by vasopressin and isoproterenol was found in the fet us and the neonate. AC-5 and AC-6 mRNAs increased at day 1 and then ma rkedly decreased, paralleling the decline in AC activity. The mRNA of AC-4 did not change and that of AC-9 increased markedly until adult. I n the homozygous Brattleboro rat kidney, the expression of all these i soforms was decreased.