Microdynamics of the Phospholipid Bilayer in Cardiomyopathic Hamster Heart Cell Membrane

To investigate the microdynamics and the structural architecture of the membrane phospholipid bilayer during the course of cardiomyopathy, membrane fractions were prepared from hearts of cardiomyopathic Syrian hamsters (BIO 14.6) aged 4, 18 and 31 weeks and compared with age-matched control hamsters (F1b). Membrane cholesterol, phospholipids and phospholipid fatty acids were measured by thin-layer chromatography, gas-liquid chromatography and high performance liquid chromatography. Microdynamics of the phospholipid bilayer were determined by a nanosecond fluorometer using pulsed excitation of a fluorescent probe, diphenyl-hexatriene. At the age of 4 weeks, there was no difference in lipid compositions and microdynamics between the BIO 14.6 and F1b. At the age of 18 weeks, saturated fatty acids, 18:0 and 22:0 increased and 20:0, 20:2 and 32:4 decreased in the BIO 14.6. At the age of 31 weeks, adding to the above changes in phospholipid fatty acids, unsaturated fatty acids 20:4 and 22:6 decreased, moreover membrane phospholipids, especially phosphatidylinositol and phosphatidylethanolamine significantly decreased. The viscosity and the wobbling angle of phospholipid molecules were decreased significantly. We have previously demonstrated that intracellular Ca2+ accumulation might be responsible for the pathogenesis of cardiomyopathy. Thus, we conclude that cardiomyopathic membrane may alter its structure and function with age. These alterations in cell membranes might be involved in the cardiac hypertrophy and dysfunction through impaired Ca2+ handling in cardiomyopathic hamsters.