Electron-conformational transformations govern the temperature dependence of the cardiac ryanodine receptor gating
A. S. Moskvin+, B. I. Iaparov+, A. M. Ryvkin+*, O. E. Solovyova+*, V. S. Markhasin+*
+ Yeltsin Ural Federal University, 620083 Ekaterinburg, Russia
*Institute of Immunology and Physiology UB of the RAS, 620119 Ekaterinburg, Russia
Abstract
Temperature influences many aspects of cardiac
excitation-contraction coupling,
in particular, hypothermia increases the open
probability (Popen) of cardiac sarcoplasmic reticulum (SR)
Ca2+-release channels
(ryanodine-sensitive RyR channels) rising the SR Ca2+
load in mammalian
myocytes. However, to the best of our knowledge,
no theoretical models are
available for that effect.
Traditional Markov chain models do not provide a reasonable molecular
mechanistic insight on the origin of the temperature effects.
Here in the paper we address a simple physically clear
electron-conformational model to describe the RyR gating
and argue that a synergetic
effect of external thermal fluctuation forces
(Gaussian-Markovian noise)
and internal friction via the temperature
stimulation/suppression of the
open-close RyR tunneling probability can be considered as a main contributor
to temperature effects on the RyR gating. Results of the computer modeling
allowed us to successfully reproduce
all the temperature effects observed for
an isolated RyR gating in vitro
under reducing the temperature: increase in
Popen and mean open time without any
significant effect on mean closed time.