Cat carotid body chemosensory discharge (in vitro) is insensitive to charybdotoxin.
Charybdotoxin (ChTX), a venom protein, suppresses Ca2+-activated K+ (K+(Ca)) currents in the glomus cell of neonatal rat carotid body. If it works similarly for cat carotid body chemoreceptors, charybdotoxin is expected to stimulate the chemosensory discharge during normoxia, and particularly hypoxia and hypercapnia. We studied the effects of charybdotoxin (20-40 nM) in vitro (perfused/superfused) on the cat carotid chemosensory discharge, and simultaneously tissue PO2 (PtiO2), as a measure of positive control. ChTX (20 nM) only increased PtiO2 and decreased carotid chemosensory discharge during hypoxia, indicating vasodilation. We conclude that K+(Ca) channels do not appear to play a significant role in chemotransduction in the cat carotid body.
Osanai
S
S
Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia 19104-6085, USA.
Buerk
D G
DG
Mokashi
A
A
Chugh
D K
DK
Lahiri
S
S
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002344:Carotid Body / Q000187:drug effects*; D002415:Cats; D015687:Cell Hypoxia / Q000187:drug effects; D018999:Charybdotoxin / Q000494:pharmacology*; D002628:Chemoreceptor Cells / Q000187:drug effects*; D005260:Female; D006935:Hypercapnia / Q000378:metabolism; D066298:In Vitro Techniques; D016014:Linear Models; D008297:Male; D010100:Oxygen / Q000378:metabolism; D010313:Partial Pressure; D015221:Potassium Channels / Q000187:drug effects*
D015221:Potassium Channels; D018999:Charybdotoxin; D010100:Oxygen; D002118:Calcium