Proteomic differential expression of cardiomyocyte after hypoxia preconditioning was investigated and protein spots with significant difference were identified using 2-D electrophoresis (2-DE) and mass spectrometry to understand the intracellular mechanism of preconditioning. Cultured cardiomyocytes of neonatal Sprague-Dawley rat have been divided into two groups: hypoxia preconditioning (HPC), and control (C) ones. After protein extraction, two-dimensional polyacrylamide gel electrophoresis, Coomassie Brillant Blue R-250 staining, followed by image analysis, was used to screen protein patterns of normal and cardiomyocytes after HPC for quantitative and qualitative differences in protein expression. Three protein spots with significant difference were picked out and subjected to in-gel digest and MALDI-TOF for indetification. More than 529 protein spots were detected on each CBB R-250-stained gel and a match rate 78%±7.5% was achieved. The results also showed that 18 protein spots displayed quantitative changes in expression after HPC, of which, 12 proteins were decreased in abundance and 6 proteins showed higher expression. After mass spectrometry analysis, three protein spots were identified as myosin light polypeptide 3, nucleoside diphosphate kinase and calreticulin. HPC induced proteomic changes in cardiomyocyte. The decreased expression of myosin light polypeptide 3, and the increased expression of nucleoside diphosphate kinase and calreticulin induced by hypoxia preconditioning may be involved in the cardioprotection via decreasing contractibility of cardiomyocytes, activating G protein, and decreasing calcium concentration. It is helpful to discuss mechanism of preconditioning on cell level that can investigate proteomic differential expression of cardiomyocyte after hypoxia preconditioning.

Key words: hypoxia preconditioning, cardiomyocyte, proteome, two-dimensional electrophoresis, mass spectrometry