Intravascularly applied K(+)-channel blockers suppress differently the positive endocochlear potential maintained by vascular perfusion.
We studied the effects of several K+ channel blockers on the positive endocochlear potential (EP) of guinea pigs undergoing perfusion via the anterior inferior cerebellar artery. The EP level was reversibly suppressed by 50-60% in the presence of Ba2+ (2 mM), quinine (2 mM) or verapamil (1 mM) in the perfusate, but not significantly affected by tetraethylammonium (20 mM) or 4-aminopyridine (5 mM). Although the effective site(s) of these blockers at the cell level has not been located yet, these findings indicate an important role for a K+ conductance in the generation of the EP.
Takeuchi
S
S
Department of Physiology, Kochi Medical School, Nankoku, Japan.
Kakigi
A
A
Takeda
T
T
Saito
H
H
Irimajiri
A
A
D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage / Q000633:toxicity; D000818:Animals; D001464:Barium / Q000008:administration & dosage / Q000633:toxicity; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000633:toxicity; D002531:Cerebellum / Q000098:blood supply; D003055:Cochlear Microphonic Potentials / Q000187:drug effects*; D006168:Guinea Pigs; D026902:Potassium Channel Blockers; D011803:Quinine / Q000008:administration & dosage / Q000633:toxicity; D013316:Stria Vascularis / Q000187:drug effects* / Q000378:metabolism; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000008:administration & dosage / Q000633:toxicity; D014700:Verapamil / Q000008:administration & dosage / Q000633:toxicity
D018712:Analgesics, Non-Narcotic; D002121:Calcium Channel Blockers; D026902:Potassium Channel Blockers; D013757:Tetraethylammonium Compounds; D001464:Barium; D019789:Tetraethylammonium; D011803:Quinine; D014700:Verapamil