Appearance of Cytosolic Albumin-Like Protein in Microsomal Fraction of Isolated Rabbit Heart during Global Ischemia

Abstract

Isolated rabbit hearts were subjected to hypothermic global ischemia for 1h and subsequent to normothermic Langendorff-reperfusion for 40min. Composition of the protein in the sarcoplasmic reticulum-enriched microsomal fraction was analyzed. Ischemia increased, whereas reperfusion decreased, the levels of a 65-kDa protein. The amino acid sequence in the N-terminal region of this 65-kDa protein was E-A-H-K-S-E-I-A-H-X-F-N-D-V-G-E-E, which resembled the antagonist protein (cytosolic Ca²⁺ uptake inhibitor antagonist protein) found in rabbit heart cytosol (Xu and Narayanan (1994) Mol. Cell. Biochem., 132, 7-14). Thus, ischemia may induce cytosolic albumin to associate with the microsomal fraction of cardiac membranes.