EFFECTS OF CYCLIC NUCLEOTIDES ON MAMMALIAN MOTOR-NERVE TERMINALS

  • 1 January 1976
    • journal article
    • research article
    • Vol. 199  (3) , 544-552
Abstract
The effects of several cyclic nucleotides on in vivo cat soleus nerves and muscles was examined. The reagents were administered by rapid close intra-arterial injection while electrical activity in single motor axons and contractile activity in the whole muscle were monitored. Cyclic N6-2''-O-dibutyryl AMP (dibutyryl cAMP) initiated bursts of action potentials in unstimulated axons. It also caused the occurrence of stimulus bound repetitive potentials in stimulated axons. It caused the muscle to undergo a series of rapid asynchronous contractions and potentiated the strength of stimulus-evoked contractions. Monobutyryl cAMP produced similar responses, but was less potent than dibutyryl cAMP. cAMP produced only a small, transient depression of neuromuscular transmission. There was no response to dibutyryl cGMP or sodium butyrate. None of these reagents affected denervated muscle. cAMP-like materials that can penetrate nerve membranes may cause depolarization of motor nerve terminals, prolongation of the depolarization of the terminal initiated by an action potential and release of transmitter.