Abstract: Objective To study the intracellular calcium ([Ca²⁺ ]i) in myocardial cell of obesity rats induced by high-fat diet. Methods Male Sprague-Dawley (SD) rats were divided into obesity resistant (OR, n=15), normal (Nor, n=15) and obesity prone (OP, n=15) group after fed with high-fat diet for 10 weeks. Their body fat and serum lipids were measured. Myocardial cells were isolated with Langendorff perfusion and [Ca²⁺]i was measured with calcium indicator Fluo-3/AM and laser scanning confocal microscope after KCl depolarization and caffeine- induced. Results Compared with those in Nor and OR rats, the epididymal fat, perirenal fat, omental fat and body fat increased in OP rats (P<0.05), as well as the the level of total cholesterol, triglyceride and low density lipoprotein (P<0.05); the vary of [Ca²⁺]i elevation and restoration were lower (P<0.05). Conclusion The vary of [Ca²⁺ ]i elevation decreases in OP rats after KCl depolarization and caffeine-induced, that may associated with arrhythmia in obesity rats.

Key words: obesity, intracellular calcium, arrhythmia, laser scanning confocal microscope, rats