Ischemia-induced increase of stiffness of αB-crystallin/HSPB2-deficient myocardium
- 136 Downloads
The two small heat shock proteins (sHSPs), αB-crystallin and HSPB2, have been shown to translocate within a few minutes of cardiac ischemia from the cytosol to myofibrils; and it has been suggested that their chaperone-like properties might protect myofibrillar proteins from unfolding or aggregation during stress conditions. Further evidence of an important role for HSPs in muscle function is provided by the fact that mutations of the αB-crystallin gene cause myopathy and cardiomyopathy. In the present study, we subjected isolated papillary muscles of αB-crystallin/HSPB2-deficient mice to simulated ischemia and reperfusion. During ischemia in αB-crystallin/HSPB2-deficient muscles, the development of contracture started earlier and reached a higher value compared to the wildtype mice. The recovery of contracture of αB-crystallin/HSPB2-deficient muscles was also attenuated during the simulated reperfusion period. However, twitch force was not significantly altered at any time of the experiment. This suggests that during ischemic insults, αB-crystallin/HSPB2 may not be important for the contraction process itself, but rather serve to maintain muscular elasticity.
We are grateful to Heike Arthen for excellent technical assistance. This study was supported by the Deutsche Forschungsgemeinschaft (SFB 355).
- 2.Bennardini F, Wrzosek A, Chiesi M (1992) AlphaB-crystallin in cardiac tissue. Association with actin and desmin filaments. Circ Res 71:288–294Google Scholar
- 7.Chiesi M, Longoni S, Limbruno U (1990) Cardiac alpha-crystallin. III. Involvement during heart ischemia. Mol Cell Biochem 97:129–136Google Scholar
- 22.Keller TC (1997) Muscle structure. Molecular bungees. Nature 387:233–235Google Scholar
- 25.Marban E, Kitakaze M, Koretsune Y, Yue DT, Chacko VP, Pike MM (1990) Quantification of [Ca2+]i in perfused hearts. Critical evaluation of the 5F-BAPTA and nuclear magnetic resonance method as applied to the study of ischemia and reperfusion. Circ Res 66:1255–1267Google Scholar