Publication
Large-conductance calcium-activated potassium channels in neonatal rat intracardiac ganglion neurons
Publisher:
Springer Science and Business Media LLC
Date:
28-11-2000
DOI:
10.1007/S004240000471
Abstract: The properties of single Ca2+-activated K+ (BK) channels in neonatal rat intracardiac neurons were investigated using the patch-cl recording technique. In symmetrical 140 mM K+, the single-channel slope conductance was linear in the voltage range -60/+60 mV, and was 207+/-19 pS. Na+ ions were not measurably permeant through the open channel. Channel activity increased with the cytoplasmic free Ca2+ concentration ([Ca2+]i) with a Hill plot giving a half-saturating [Ca2+] (K0.5) of 1.35 microM and slope of approximately equals 3. The BK channel was inhibited reversibly by external tetraethylammonium (TEA) ions, charybdotoxin, and quinine and was resistant to block by 4-aminopyridine and apamin. Ionomycin (1-10 microM) increased BK channel activity in the cell-attached recording configuration. The resting activity was consistent with a [Ca2+]i or =0.3 microM. TEA (0.2-1 mM) increased the action potential duration approximately equals 1.5-fold and reduced the litude and duration of the afterhyperpolarization (AHP) by 26%. Charybdotoxin (100 nM) did not significantly alter the action potential duration or AHP litude but reduced the AHP duration by approximately equals 40%. Taken together, these data indicate that BK channel activation contributes to the action potential and AHP duration in rat intracardiac neurons.