Muscarinic M-current inhibition via G alpha q/11 and alpha-adrenoceptor inhibition of Ca2+ current via G alpha o in rat sympathetic neurones

J Physiol. 1994 Jun 15;477 ( Pt 3)(Pt 3):415-22. doi: 10.1113/jphysiol.1994.sp020203.


1. Microinjection of selective antibodies into superior cervical ganglion (SCG) neurones has identified the G-protein alpha-subunits mediating muscarinic receptor inhibition of M-type K+ current (IK(M)) and alpha-adrenoceptor inhibition of Ca2+ current (ICa). 2. Antibodies specific for G alpha q/11, but not those for G alpha o, reduced M-current inhibition by the muscarinic agonist oxotremorine-M, whereas anti-G alpha o antibodies, but not anti-G alpha q/11 or anti-G alpha i1-3 antibodies, reduced calcium current inhibition by noradrenaline. 3. Immunoblots with specific anti-G-protein antibodies demonstrated the presence of both G alpha q and G alpha 11, while G alpha o1 (but virtually no G alpha o2) was present. 4. We conclude that M1 muscarinic receptor inhibition of IK(M) is transduced by G alpha q and/or G alpha 11, and that G alpha o transduces alpha-adrenoceptor inhibition of ICa.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic alpha-Agonists / pharmacology*
  • Animals
  • Antibodies / immunology
  • Calcium / physiology*
  • Calcium Channel Blockers / pharmacology
  • Electric Conductivity
  • GTP-Binding Proteins / immunology
  • GTP-Binding Proteins / physiology*
  • Ganglia, Sympathetic / cytology
  • Ganglia, Sympathetic / physiology*
  • Neurons / physiology
  • Potassium Channel Blockers*
  • Potassium Channels / classification
  • Potassium Channels / physiology
  • Rats
  • Receptors, Muscarinic / physiology*


  • Adrenergic alpha-Agonists
  • Antibodies
  • Calcium Channel Blockers
  • Potassium Channel Blockers
  • Potassium Channels
  • Receptors, Muscarinic
  • GTP-Binding Proteins
  • Calcium