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Remote ischemic preconditioning of cardiomyocytes inhibits the mitochondrial permeability transition pore independently of reduced calcium-loading or sarcKATP channel activation.

Turrell HE, Thaitirarot C, Crumbie H, Rodrigo G - Physiol Rep (2014)

Bottom Line: However, only conventional-IPC reduced the Ca(2+)-loading during metabolic inhibition and this was independent of any change in sarcKATP channel activity but was associated with a reduction in Na(+)-loading, reflecting a decrease in Na/H exchanger activity.These data show that remote-IPC inhibits MPT pore opening to a similar degree as conventional IPC, however, the contribution of MPT pore inhibition to protection against reperfusion injury is independent of Ca(2+)-loading in remote IPC.We suggest that inhibition of the MPT pore and not Ca(2+)-loading is the common link in cardioprotection between conventional and remote IPC.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK.

No MeSH data available.


Related in: MedlinePlus

The TMRE fluorescence recorded from conventional and remotely preconditioned myocytes as an indicator of mitochondrial transition pore opening. (A) Fluorescent image of a control myocyte continuously illuminated, illustrating the photodamage due to continuous illumination of TMRE loaded myocyte, at time 0 sec, 210 sec, 390 sec, and 580 sec of illumination. The large increase in fluorescence is visible at 390 sec and at 580 sec the myocyte can be seen to develop a rigor contracture. (B) Trace of TMRE fluorescence from a control myocyte (black circles) and remote IPC myocyte (light‐gray circles). Data points were fitted with a sigmoidal curve and time to increase in fluorescence to 90% of max determined. (C) Mean data ± SEM of the time to 90% increase in fluorescence from control naïve‐myocytes (black), conventional IPC‐myocytes (dark gray), rIPC myocytes (light gray), and control myocytes in the presence of Sanglifehrin‐A (0.5 μmol/L). **P < 0.01, ***P < 0.001, one‐way ANOVA followed by Tukey's post hoc test for significance. Control naïve myocytes = 4 hearts; 22 observations, conventional IPC myocytes = 4; 15, remote IPC = 4; 18, and control + Sanglifehrin‐A = 4; 14.
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fig08: The TMRE fluorescence recorded from conventional and remotely preconditioned myocytes as an indicator of mitochondrial transition pore opening. (A) Fluorescent image of a control myocyte continuously illuminated, illustrating the photodamage due to continuous illumination of TMRE loaded myocyte, at time 0 sec, 210 sec, 390 sec, and 580 sec of illumination. The large increase in fluorescence is visible at 390 sec and at 580 sec the myocyte can be seen to develop a rigor contracture. (B) Trace of TMRE fluorescence from a control myocyte (black circles) and remote IPC myocyte (light‐gray circles). Data points were fitted with a sigmoidal curve and time to increase in fluorescence to 90% of max determined. (C) Mean data ± SEM of the time to 90% increase in fluorescence from control naïve‐myocytes (black), conventional IPC‐myocytes (dark gray), rIPC myocytes (light gray), and control myocytes in the presence of Sanglifehrin‐A (0.5 μmol/L). **P < 0.01, ***P < 0.001, one‐way ANOVA followed by Tukey's post hoc test for significance. Control naïve myocytes = 4 hearts; 22 observations, conventional IPC myocytes = 4; 15, remote IPC = 4; 18, and control + Sanglifehrin‐A = 4; 14.

Mentions: We have previously shown that additional mechanisms over and above that of Ca2+‐loading during MI, are important in the recovery of IPC‐myocytes during reenergization (Rodrigo and Samani 2008) and that inhibition of the MPT pore protects naïve‐myocytes against loss of function and Ca2+‐homeostasis following MI and reenergization (Rodrigo and Standen 2005a). The use of TMRE to measure mitochondrial membrane potential has been adopted as an indirect marker of MPT‐pore opening (Hausenloy et al. 2004). However, as MI results in depolarization of the mitochondrial membrane potential due to the inhibition of the electron transport chain (Lawrence et al. 2001), we were not able use this technique to look at opening of MPT pore in response to MI. We therefore looked at the ability of both IPC and rIPC of naïve myocytes to delay the opening of MPT pore in response to stress induced by illumination of myocytes loaded with TMRE (Hausenloy et al. 2004). MPT pore opening was taken as the time to increase in TMRE fluorescence to 90% of maximum (Fig. 8A and B, see methods).


Remote ischemic preconditioning of cardiomyocytes inhibits the mitochondrial permeability transition pore independently of reduced calcium-loading or sarcKATP channel activation.

Turrell HE, Thaitirarot C, Crumbie H, Rodrigo G - Physiol Rep (2014)

The TMRE fluorescence recorded from conventional and remotely preconditioned myocytes as an indicator of mitochondrial transition pore opening. (A) Fluorescent image of a control myocyte continuously illuminated, illustrating the photodamage due to continuous illumination of TMRE loaded myocyte, at time 0 sec, 210 sec, 390 sec, and 580 sec of illumination. The large increase in fluorescence is visible at 390 sec and at 580 sec the myocyte can be seen to develop a rigor contracture. (B) Trace of TMRE fluorescence from a control myocyte (black circles) and remote IPC myocyte (light‐gray circles). Data points were fitted with a sigmoidal curve and time to increase in fluorescence to 90% of max determined. (C) Mean data ± SEM of the time to 90% increase in fluorescence from control naïve‐myocytes (black), conventional IPC‐myocytes (dark gray), rIPC myocytes (light gray), and control myocytes in the presence of Sanglifehrin‐A (0.5 μmol/L). **P < 0.01, ***P < 0.001, one‐way ANOVA followed by Tukey's post hoc test for significance. Control naïve myocytes = 4 hearts; 22 observations, conventional IPC myocytes = 4; 15, remote IPC = 4; 18, and control + Sanglifehrin‐A = 4; 14.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4255825&req=5

fig08: The TMRE fluorescence recorded from conventional and remotely preconditioned myocytes as an indicator of mitochondrial transition pore opening. (A) Fluorescent image of a control myocyte continuously illuminated, illustrating the photodamage due to continuous illumination of TMRE loaded myocyte, at time 0 sec, 210 sec, 390 sec, and 580 sec of illumination. The large increase in fluorescence is visible at 390 sec and at 580 sec the myocyte can be seen to develop a rigor contracture. (B) Trace of TMRE fluorescence from a control myocyte (black circles) and remote IPC myocyte (light‐gray circles). Data points were fitted with a sigmoidal curve and time to increase in fluorescence to 90% of max determined. (C) Mean data ± SEM of the time to 90% increase in fluorescence from control naïve‐myocytes (black), conventional IPC‐myocytes (dark gray), rIPC myocytes (light gray), and control myocytes in the presence of Sanglifehrin‐A (0.5 μmol/L). **P < 0.01, ***P < 0.001, one‐way ANOVA followed by Tukey's post hoc test for significance. Control naïve myocytes = 4 hearts; 22 observations, conventional IPC myocytes = 4; 15, remote IPC = 4; 18, and control + Sanglifehrin‐A = 4; 14.
Mentions: We have previously shown that additional mechanisms over and above that of Ca2+‐loading during MI, are important in the recovery of IPC‐myocytes during reenergization (Rodrigo and Samani 2008) and that inhibition of the MPT pore protects naïve‐myocytes against loss of function and Ca2+‐homeostasis following MI and reenergization (Rodrigo and Standen 2005a). The use of TMRE to measure mitochondrial membrane potential has been adopted as an indirect marker of MPT‐pore opening (Hausenloy et al. 2004). However, as MI results in depolarization of the mitochondrial membrane potential due to the inhibition of the electron transport chain (Lawrence et al. 2001), we were not able use this technique to look at opening of MPT pore in response to MI. We therefore looked at the ability of both IPC and rIPC of naïve myocytes to delay the opening of MPT pore in response to stress induced by illumination of myocytes loaded with TMRE (Hausenloy et al. 2004). MPT pore opening was taken as the time to increase in TMRE fluorescence to 90% of maximum (Fig. 8A and B, see methods).

Bottom Line: However, only conventional-IPC reduced the Ca(2+)-loading during metabolic inhibition and this was independent of any change in sarcKATP channel activity but was associated with a reduction in Na(+)-loading, reflecting a decrease in Na/H exchanger activity.These data show that remote-IPC inhibits MPT pore opening to a similar degree as conventional IPC, however, the contribution of MPT pore inhibition to protection against reperfusion injury is independent of Ca(2+)-loading in remote IPC.We suggest that inhibition of the MPT pore and not Ca(2+)-loading is the common link in cardioprotection between conventional and remote IPC.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK.

No MeSH data available.


Related in: MedlinePlus