2 TYPES OF VOLTAGE-GATED K-CHANNELS IN CAROTID-BODY CELLS OF ADULT CATS

Citation
Cl. Chou et M. Shirahata, 2 TYPES OF VOLTAGE-GATED K-CHANNELS IN CAROTID-BODY CELLS OF ADULT CATS, Brain research, 742(1-2), 1996, pp. 34-42
Citations number
44
Categorie Soggetti
Neurosciences
Journal title
ISSN journal
00068993
Volume
742
Issue
1-2
Year of publication
1996
Pages
34 - 42
Database
ISI
SICI code
0006-8993(1996)742:1-2<34:2TOVKI>2.0.ZU;2-0
Abstract
The purpose of this study was to investigate if the oxygen-sensitive K channel is present in the carotid body cells of adult cats, and if al l carotid body cells express the oxygen-sensitive K channel. A standar d patch-clamp technique with a whole-cell configuration was applied to cultured carotid body cells from adult cats. The cells were continuou sly perfused with Krebs equilibrated with 5% CO2/air or 5% CO2/argon a t room temperature. The results showed that electrophysiologically at least two types of cells existed in cultured cat carotid body cells. O ne type expressed the oxygen sensitive K channel and the other express ed the oxygen-insensitive K channel. The oxygen-sensitive K channel wa s voltage-dependent with a threshold potential of -30 mV. No inactivat ion was observed during 30 ms of stimulation. The slope of the steady- state current-voltage curve was almost linear in the range from -30 mV to +50 mV. Hypoxia (pO(2) = 25 mmHg) reversibly depressed the K curre nt by 22%. The current was inhibited by 4-aminopyridine (10 mM) and te traethylammonium (4-25 mM), but insensitive to charybdotoxin (100 nM). The oxygen-insensitive K channel showed similar characteristics to th at of the oxygen-sensitive K channel in the threshold and the speed of activation, and the shape of I-V curve. The cat is the third species in which the oxygen-sensitive K channel was found in the carotid body. The sensitivity of K channels to oxygen may be a unique feature of ch emosensory cells, but the properties of the oxygen-sensitive K channel s are different among cats, rats, and rabbits.