Determination of alpha B crystallin aggregation: a new alternative method to assess ischemic damage of the heart.

alpha B crystallin, a heat-shock-like protein, is a major component of the soluble protein fraction of the heart and is thought to play a protective role in stress situations. During an ischemic episode, the cytosol of cardiomyocytes acidifies, thus causing the aggregation of the protein with cytoskeletal elements. After homogenization of the tissue, alpha B crystallin can then be recovered with the insoluble cell components. This study investigated the change of the solubility properties of crystallin in the ischemic heart. The distribution of crystallin in the soluble and insoluble cellular fractions was determined by centrifugation of heart homogenates and immunoblot analysis with anti-alpha B crystallin antibodies. The proportion of aggregated alpha B-crystallin increased in hearts reperfused after total normothermic ischemia of increasing severity. alpha B crystallin aggregation was proportional to the amount of lactate dehydrogenase activity released by the hearts and was inversely correlated to the ability of the hearts to recover contractile activity after the ischemic episode. This study shows that the amount of aggregated crystallin can be used as a new marker for the ischemic damage of the heart. Biopsies of a few milligrams are sufficient for the analysis.