Tokimasa T, Shirasaki T, Kuba K
Department of Physiology, Tokai University School of Medicine, Isehara, Japan.
Neurosci Lett. 1997 Nov 7;236(3):123-6. doi: 10.1016/s0304-3940(97)00791-x.
Intracellular Ca2+ concentration ([Ca]i) was measured following the activation of an inward Ca2+ current and subsequent potentiation of an M-type K+ current (IM) in bullfrog sympathetic neurons. Fura-2 was used as an indicator for [Ca]i. The fluorescence ratio at 340 and 380 nm (F340/F380) was elevated from 0.36 to 1.22 when IM was potentiated by 68% following the Ca2+ current. Based on the in vivo calibration curve obtained from cells permeabilized with digitonin (20 microM), the F340/F380 value of 1.22 was equivalent to a [Ca]i of 0.97 microM. We therefore propose that a rise in [Ca]i into the micromolar range can lead to the potentiation of IM in amphibian autonomic neurons.
在牛蛙交感神经元中，测量内向Ca2+电流激活以及随后M型K+电流（IM）增强后细胞内Ca2+浓度（[Ca]i）。Fura-2用作[Ca]i的指示剂。当Ca2+电流后IM增强68%时，340和380nm处的荧光比率（F340/F380）从0.36升高到1.22。根据用洋地黄皂苷（20 microM）通透处理的细胞获得的体内校准曲线，F340/F380值为1.22相当于[Ca]i为0.97 microM。因此，我们提出[Ca]i升高到微摩尔范围可导致两栖动物自主神经元中IM的增强。
