Ability of some K+ channel blockers to reverse inhibition of electrically evoked contractions of longitudinal muscle-myenteric plexus.
Blockers selective for different potassium (K+) channels were examined for their ability to reverse inhibition of electrically evoked contractions of longitudinal muscle-myenteric plexus (lm-mp) by adenosine analogs. Cyclohexyl adenosine (CHA) was selected for these studies, since it effectively inhibited contraction (EC50 33 nM). 4-aminopyridine (4-AP) antagonized the inhibition by the adenosine analog, but also stimulated contraction by itself. alpha- and gamma-dendrotoxin produced the most profound reversal of CHA-induced inhibition, while producing a minimal contraction alone. Other blockers produced only nominal reversal of the CHA-induced inhibition. These results suggest that inhibition by CHA is mediated via activation of an alpha- and gamma-dendrotoxin-sensitive K+ channel.
Kelly
G
G
Department of Physiology, University of Alberta, Edmonton, Canada.
Sun
Y D
YD
Benishin
C G
CG
D015761:4-Aminopyridine / Q000494:pharmacology; D000241:Adenosine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D006168:Guinea Pigs; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009197:Myenteric Plexus / Q000187:drug effects*; D010455:Peptides / Q000494:pharmacology; D026902:Potassium Channel Blockers; D012910:Snake Venoms
D010455:Peptides; D026902:Potassium Channel Blockers; D012910:Snake Venoms; C081639:dendrotoxin, gamma; C081705:dendrotoxin A; C027513:N(6)-cyclohexyladenosine; D015761:4-Aminopyridine; D000241:Adenosine