当前位置： SCI文献检索 > BIOPHYSICAL JOURNAL期刊下所有文献 > Voltage and temperature dependence of single K+ channels isolated from canine cardiac sarcoplasmic reticulum.

Voltage and temperature dependence of single K+ channels isolated from canine cardiac sarcoplasmic reticulum.

Abstract：

:The temperature and voltage dependence of gating and conductance of sarcoplasmic reticulum K+ channels (S-R K+) isolated from adult canine hearts were studied using the reconstituted bilayer technique. Fusion of vesicles from this preparation frequently resulted in the incorporation of a single channel. Only bilayers into which a single S-R K+ channel had fused were studied. The three conductance states of the channel, fully open (O2), substate conductance (O1), and closed (C) were studied as a function of voltage (-50 to +50 mV) and temperature (16 to 37 degrees C). Permeation through the O1 state showed the same temperature dependence as the O2 state corresponding to an enthalpy of permeation of 4.1-4.2 kcal/mol, which is similar to that for K+ diffusion through water. As expected, increased temperature increased the frequency of gating transitions and shortened the average dwell time spent in any conductance state. Over the range of 25 to 37 degrees C, the average dwell time spent in the O1, O2, and C states decreased by 44 +/- 11, 36 +/- 13, and 78 +/- 7% (n = 3 to 4 channels), respectively. The ratio of probabilities between the various conductance states was not strongly temperature sensitive. Analysis of the voltage dependence of this channel was carried out at 37 degrees C and revealed that the dwell times of the O1 and O2 states were voltage insensitive and the probability ratio (PO2:PO1) was approximately 7 and was voltage insensitive. Nonlinear least-squares analysis of dwell times revealed that the closed state was biexponential and was thus composed of a fast (Cf) and a slow (C8) component.Tcf was voltage insensitive with an average value of 5.9 ms, whereas tau c was approximately two orders of magnitude slower and was voltage dependent. The voltage dependence of Cs was described by Tau c (ms) = exp(-0.025-(Vm (mV) - 250)).

journal_name

Biophys J

journal_title

Biophysical journal

authors

Shen WK,Rasmusson RL,Liu QY,Crews AL,Strauss HC

doi

10.1016/S0006-3495(93)81100-7

subject

Has Abstract

pub_date

1993-08-01 00:00:00

pages

747-54

issue

eissn

0006-3495

issn

1542-0086

pii

S0006-3495(93)81100-7

journal_volume

pub_type

杂志文章

在线工具

Voltage and temperature dependence of single K+ channels isolated from canine cardiac sarcoplasmic reticulum.