Role of stretch-activated channels on the stretch-induced changes of rat atrial myocytes.
The role of stretch-activated channels (SACs) on the stretch-induced changes of rat atrial myocytes was studied using a computer model that incorporated various ion channels and transporters including SACs. A relationship between the extent of the stretch and the activation of SACs was formulated in the model based on experimental findings to reproduce changes in electrical activity and Ca(2+) transients by stretch. Action potentials (APs) were significantly changed by the activation of SACs in the model simulation. The duration of the APs decreased at the initial fast phase and increased at the late slow phase of repolarisation. The resting membrane potential was depolarised from -82 to -70 mV. The Ca(2+) transients were also affected. A prolonged activation of SACs in the model gradually increased the amplitude of the Ca(2+) transients. The removal of Ca((2+)) permeability through SACs, however, had little effect on the stretch-induced changes in electrical activity and Ca(2+) transients in the control condition. In contrast, the removal of the Na(+) permeability nearly abolished these stretch-induced changes. Plotting the peaks of the Ca((2+)) transients during the activation of the SACs along a time axis revealed that they follow the time course of the Na(i)(+) concentration. The Ca((2+)) transients were not changed when the Na(i)(+) concentration was fixed to a control value (5.4mM). These results predicted by the model suggest that the influx of Na(+) rather than Ca(2+) through SACs is more crucial to the generation of stretch-induced changes in the electrical activity and associated Ca(2+) transients of rat atrial myocytes.
Youm
Jae Boum
JB
Mitochondrial Signaling Laboratory, Department of Physiology and Biophysics, College of Medicine, Cardiovascular and Metabolic Disease Center, Biohealth Products Research Center, Inje University, Busan 614-735, Republic of Korea.
Han
Jin
J
Kim
Nari
N
Zhang
Yin-Hua
YH
Kim
Euiyong
E
Joo
Hyun
H
Hun Leem
Chae
C
Joon Kim
Sung
S
Cha
Kyung A
KA
Earm
Yung E
YE
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003198:Computer Simulation; D006325:Heart Atria / Q000166:cytology; D015640:Ion Channel Gating; D040542:Mechanotransduction, Cellular; D008564:Membrane Potentials / Q000502:physiology; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D002118:Calcium