ATP-sensitive K+ channel activation by calcitonin gene-related peptide and protein kinase A in pig coronary arterial smooth muscle

J Physiol. 1998 Feb 15;507 ( Pt 1)(Pt 1):117-29. doi: 10.1111/j.1469-7793.1998.117bu.x.


1. We used patch clamp to study whole-cell K+ currents activated by calcitonin gene-related peptide (CGRP) in smooth muscle cells freshly dissociated from pig coronary arteries. 2. CGRP (50 nM) activated an inward current at -60 mV in symmetrical 140 mM K+ that was blocked by glibenclamide (10 microM), an inhibitor of ATP-sensitive potassium (KATP) channels. CGRP-induced currents were larger in cells dialysed with 0.1 mM ATP than with 3.0 mM ATP. 3. Forskolin (10 microM) activated a glibenclamide-sensitive current, as did intracellular dialysis with cAMP (100 microM). The catalytic subunit of cAMP-dependent protein kinase (protein kinase A, PKA), added to the pipette solution, activated equivalent currents in five out of twelve cells. 4. CGRP-induced currents were reduced by the PKA inhibitors adenosine 3',5'-cyclic monophosphorothioate, RP-isomer, triethylammonium salt (Rp-cAMPS; 100 microM) and N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulphonamide+ ++ dihydrochloride (H-89; 1 microM), and abolished by inclusion of a PKA inhibitor peptide in the pipette solution. 5. The beta-adrenergic agonist isoprenaline (10 microM) also activated a glibenclamide-sensitive K+ current. 6. CGRP-induced currents were unaffected by the inhibitor of cGMP-dependent protein kinase (PKG) KT5823 (1 microM). Sodium nitroprusside (10 microM) did not activate a glibenclamide-sensitive current in cells held at -60 mV, but did activate an outward current at +60 mV that was abolished by KT5823, or by 100 nM iberiotoxin (an inhibitor of BKCa channels). 7. Our findings suggest that CGRP activates coronary KATP channels through a pathway that involves adenylyl cyclase and PKA, but not PKG.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / physiology*
  • Adenylyl Cyclases / metabolism
  • Adrenergic beta-Agonists / pharmacology
  • Animals
  • Arteries / metabolism
  • Calcitonin Gene-Related Peptide / pharmacology*
  • Coronary Vessels / metabolism*
  • Cyclic AMP / physiology
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Cyclic AMP-Dependent Protein Kinases / pharmacology*
  • Cyclic GMP-Dependent Protein Kinases / physiology
  • Electric Conductivity
  • Enzyme Activation / physiology
  • Enzyme Inhibitors / pharmacology
  • Isoproterenol / pharmacology
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / metabolism*
  • Potassium Channels / drug effects*
  • Potassium Channels / physiology
  • Swine


  • Adrenergic beta-Agonists
  • Enzyme Inhibitors
  • Potassium Channels
  • Adenosine Triphosphate
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Cyclic GMP-Dependent Protein Kinases
  • Adenylyl Cyclases
  • Calcitonin Gene-Related Peptide
  • Isoproterenol