大鼠胰腺β细胞离子通道的一些特性

实验以单个Ｗｉｓｔａｒ大鼠胰腺β细胞为对象,用穿孔膜片箝和细胞贴附式记录技术研究ＡＴＰ敏感Ｋ＾＋通道（ＫＡＴＰ）、延迟整流型Ｋ＾＋通道（ＫＤＲ）、Ｃａ＾２＋通道和Ｎａ＾＋通道的有关特性。结果表明：⑴ＫＡＴＰ通道的内流电导约６５ｐＳ,外流电导约３１ｐＳ,反转电位在－６０ｍＶ左右;⑵ＫＤＲ通道在延迟２０ｍｓ后达到最大激活,ＫＤＲ电流约为ＫＡＴＰ的１／３;⑶钙电流在０ｍＶ左右达到４０－６０ｐＡ的峰值,Ｌ

Ion channels in rat pancreatic beta cells

Using perforated and cell-attached patch clamp techniques, the characteristics of ATP sensitive K(+) channels (K(ATP)), delayed rectifier K(+) channels (K(DR)), Ca(2+) and Na+ channels on single rat pancreatic beta cell membranes were studied. The results showed that (1) the efflux and influx conductance of K(ATP) channels was about 31 and 65 pS respectively, and the reversal potential of K(ATP) was about 60 mV; (2) K(DR) was activated completely after a latency of 20 ms, and K(DR) was about 1/3 of K(ATP); (3) whole cell Ca(2+) current reached a peak (40 60 pA) at 0 mV; L-type Ca(2+) channel was the main Ca(2+) channel in beta cells, but other types of high voltage activated Ca(2+) channels existed as well; and 4) whole cell Na(+) current reached a peak (200 400 pA) at 10 mV; but the expression level of Na(+) channel in beta cells varied among the cells. About half of the beta cells virtually had no Na(+) currents.