Enhanced cell volume regulation: a key mechanism in local and remote ischemic preconditioning.
We have previously shown that ischemic preconditioning (IPC) protection against necrosis in whole hearts and in both fresh and cultured cardiomyocytes, as well as the improved regulatory volume decrease to hypoosmotic swelling in cardiomyocytes, is abrogated through Cl(-) channel blockade, pointing to a role for enhanced cell volume regulation in IPC. To further define this cardioprotective mechanism, cultured rabbit ventricular cardiomyocytes were preconditioned either by 10-min simulated ischemia (SI) followed by 10-min simulated reperfusion (SR), by 10-min exposure/10-min washout of remote IPC (rIPC) plasma dialysate (from rabbits subjected to repetitive limb ischemia), or by adenoviral transfection with the constitutively active PKC-ε gene. These interventions were done before cardiomyocytes were subjected to either 60- or 75-min SI/60-min SR to assess cell necrosis (by trypan blue staining), 30-min SI to assess ischemic cell swelling, or 30-min hypoosmotic (200 mosM) stress to assess cell volume regulation. Necrosis after SI/SR and both SI- and hypoosmotic stress-induced swelling was reduced in preconditioned cardiomyocytes compared with control cardiomyocytes (neither preconditioned nor transfected). These effects on necrosis and cell swelling were blocked by either Cl(-) channel blockade or dominant negative knockdown of inwardly rectifying K(+) channels with adenoviruses, suggesting that Cl(-) and K(+) movements across the sarcolemma are critical for cell volume regulation and, thereby, cell survival under hypoxic/ischemic conditions. Our results define enhanced cell volume regulation as a key common mechanism of cardioprotection by preconditioning in cardiomyocytes.
Division of Physiology and Experimental Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Pediatric Laboratory Medicine and Pathology, The Hospital for Sick Children, Toronto, Ontario, Canada;
Roberto J
RJ
Diaz
Division of Physiology and Experimental Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; and.
Kordan
K
Harvey
Division of Physiology and Experimental Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; and.
Azadeh
A
Boloorchi
Division of Physiology and Experimental Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada;
Taneya
T
Hossain
Division of Physiology and Experimental Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada;
Alina
A
Hinek
Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
Peter H
PH
Backx
Division of Physiology and Experimental Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Pediatric Laboratory Medicine and Pathology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; and gregory.wilson@sickkids.ca.
Gregory J
GJ
Wilson
D000818:Animals; D048429:Cell Size; D018118:Chloride Channels / Q000378:metabolism; D007511:Ischemia; D019157:Ischemic Preconditioning, Myocardial; D009203:Myocardial Infarction / Q000503:physiopathology* / Q000517:prevention & control; D032383:Myocytes, Cardiac / Q000502:physiology*; D009336:Necrosis / Q000503:physiopathology; D015221:Potassium Channels / Q000378:metabolism; D011817:Rabbits; D015424:Reperfusion; D012508:Sarcolemma / Q000378:metabolism
D018118:Chloride Channels; D015221:Potassium Channels
cardiomyocytes; cell swelling; cell volume regulation; chloride channels; protein kincase C-ε; remote ischemic preconditioning