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

W. K. Shen, R. L. Rasmusson, Q. Y. Liu, A. L. Crews, H. C. Strauss

Research output: Contribution to journalArticle

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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°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°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°C and revealed that the dwell times of the O1 and O2 states were voltage insensitive and the probability ratio (P(O2):P(O1)) 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 (C(f)) and a slow (C(s)) component. τ(C(f)) was voltage insensitive with an average value of 5.9 ms, whereas τ(C(s)) was approximately two orders of magnitude slower and was voltage dependent. The voltage dependence of C(s) was described by τ(C(s)) (ms) = exp(-0.025 · (V(m)(mV) - 250)).

Original languageEnglish (US)
Pages (from-to)747-754
Number of pages8
JournalBiophysical Journal
Volume65
Issue number2
StatePublished - 1993
Externally publishedYes

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Sarcoplasmic Reticulum
Canidae
Temperature
Least-Squares Analysis
Water

ASJC Scopus subject areas

  • Biophysics

Cite this

Shen, W. K., Rasmusson, R. L., Liu, Q. Y., Crews, A. L., & Strauss, H. C. (1993). Voltage and temperature dependence of single K+ channels isolated from canine cardiac sarcoplasmic reticulum. Biophysical Journal, 65(2), 747-754.

Voltage and temperature dependence of single K+ channels isolated from canine cardiac sarcoplasmic reticulum. / Shen, W. K.; Rasmusson, R. L.; Liu, Q. Y.; Crews, A. L.; Strauss, H. C.

In: Biophysical Journal, Vol. 65, No. 2, 1993, p. 747-754.

Research output: Contribution to journalArticle

Shen, WK, Rasmusson, RL, Liu, QY, Crews, AL & Strauss, HC 1993, 'Voltage and temperature dependence of single K+ channels isolated from canine cardiac sarcoplasmic reticulum', Biophysical Journal, vol. 65, no. 2, pp. 747-754.
Shen, W. K. ; Rasmusson, R. L. ; Liu, Q. Y. ; Crews, A. L. ; Strauss, H. C. / Voltage and temperature dependence of single K+ channels isolated from canine cardiac sarcoplasmic reticulum. In: Biophysical Journal. 1993 ; Vol. 65, No. 2. pp. 747-754.
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