Chen F, Wetzel G T, Friedman W F, Klitzner T S
Department of Pediatrics, University of California, School of Medicine, Los Angeles 90024.
Pediatr Res. 1992 Aug;32(2):230-5. doi: 10.1203/00006450-199208000-00021.
The properties of the ATP-sensitive potassium (KATP) current were studied in freshly isolated rabbit ventricular myocytes using the patch clamp technique. Removing ATP from the bath (intracellular) solution activated a large K+ conductance in patches from neonatal cells with properties similar to those of KATP channels in other preparations. In membrane patches from neonatal ventricular myocytes, the density of KATP channels was higher than the density of inwardly rectifying K+ channels and the mean patch KATP current was approximately 10 times that of the inwardly rectifying K+ current, at a patch membrane potential of -60 mV. Glibenclamide (10 microM) in the bath solution decreased the number of functional KATP channels, the open-state probability, and the mean patch membrane current. The single-channel conductance of the KATP channel was dependent on the external K+ concentration, and the relationship between channel conductance and external K+ concentration was fit by an exponential equation. In addition, the voltage dependence, channel density, and open-state probability of this channel were compared between neonatal and adult isolated ventricular myocytes. The single-channel conductance and channel density of the KATP channel in neonatal myocytes were significantly smaller than in adult cells. These results suggest that age-related changes occur in the properties of KATP channels.
采用膜片钳技术，在新鲜分离的兔心室肌细胞中研究了ATP敏感性钾（KATP）电流的特性。从浴槽（细胞内）溶液中去除ATP可激活新生细胞膜片中的大K+电导，其特性与其他制剂中的KATP通道相似。在新生心室肌细胞膜片中，KATP通道的密度高于内向整流K+通道的密度，在膜片膜电位为-60 mV时，平均膜片KATP电流约为内向整流K+电流的10倍。浴槽溶液中的格列本脲（10 microM）减少了功能性KATP通道的数量、开放概率和平均膜片电流。KATP通道的单通道电导取决于外部K+浓度，通道电导与外部K+浓度之间呈指数方程拟合关系。此外，还比较了新生和成年分离心室肌细胞中该通道的电压依赖性、通道密度和开放概率。新生心肌细胞中KATP通道的单通道电导和通道密度明显小于成年细胞。这些结果表明，KATP通道的特性存在与年龄相关的变化。
