EXPRESSION OF ADENYLYL-CYCLASE MESSENGER-RNAS IN THE DENERVATED AND IN THE DEVELOPING MOUSE SKELETAL-MUSCLE

Changes in the activity and in the expression of adenylyl cyclase IAC) mere examined in mouse skeletal muscle after denervation and during d evelopment. Four isofarms of AC (AC2, AC6, AC7, and AC9) were detected by Northern blot analysis in gastrocnemius muscle, AC9 being the most abundant. After denervation, the levels of AC2 and AC9 mRNA decreased , whereas those of AC6 and AC7 increased. AC activity in response to s everal neurotransmitters was increased after denervation. During devel opment, AC activity was high in fetus and neonate and declined in the adult; the sensitivity of AC activity to various neurotransmitters was the highest on the third postnatal day, The levels of ACG and AC7 mRN As were high on the third postnatal day and then decreased in adult, p aralleling the decline in AC activity. AU the characteristics of AC ex pression and activity in fetus and neonate resembled those observed in denervated adult muscle. These results indicate that changes in AC ac tivity and AC mRNAs play an important role in the various physiopathol ogical states of skeletal muscle, especially during muscle atrophy.