Franciolini F, Hogg R, Catacuzzeno L, Petris A, Trequattrini C, Adams D J
Dipartmento Biologia Cellulare e Molecolare, Universita' di Perugia, Italy.
Pflugers Arch. 2001 Feb;441(5):629-38. doi: 10.1007/s004240000471.
The properties of single Ca2+-activated K+ (BK) channels in neonatal rat intracardiac neurons were investigated using the patch-clamp 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 <100 nM and the increased channel activity evoked by ionomycin was consistent with a rise in [Ca2+]i to > or =0.3 microM. TEA (0.2-1 mM) increased the action potential duration approximately equals 1.5-fold and reduced the amplitude and duration of the afterhyperpolarization (AHP) by 26%. Charybdotoxin (100 nM) did not significantly alter the action potential duration or AHP amplitude 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.
采用膜片钳记录技术研究了新生大鼠心内神经元中单个钙激活钾（BK）通道的特性。在对称的140 mM钾溶液中，单通道斜率电导在-60/+60 mV电压范围内呈线性，为207±19 pS。钠离子在开放通道中无明显通透。通道活性随胞质游离钙浓度（[Ca2+]i）增加，希尔图显示半饱和[Ca2+]（K0.5）为1.35 μM，斜率约为3。BK通道可被细胞外四乙铵（TEA）离子、蝎毒素和奎宁可逆性抑制，对4-氨基吡啶和蜂毒肽的阻断具有抗性。离子霉素（1-10 μM）在细胞贴附记录模式下增加BK通道活性。静息活性与[Ca2+]i<100 nM一致，离子霉素引起的通道活性增加与[Ca2+]i升高至≥0.3 μM一致。TEA（0.
