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Abstract:
Membrane Fusion, Sarcoplasmic Reticulum, Ethylene Glycol, Dimethylsulfoxide Fragmented sarcoplasmic reticulum (FSR) vesicles from rabbit skeletal muscle were suspended in 5 - 10% ethylene glycol (EG) or in 5, 10, or 25% dimethylsulfoxide (DMSO) and were pelleted onto flat aluminum foil disks. No vesicle fusion occurs with either 5 or 10% EG treatment and 2-2½ hours drying. After 4-5 hours drying, 5% EG-treated vesicles have established more areas of close contact and individual vesicles have begun to flatten when compared with the 10% EG vesicles. Overnight drying results in formation of extended sheets of fused membranes called double bilayers in both the 5 and 10% EG samples. In the 5% EG-treated vesicles, formation of large spaces in the pellet compresses the adjacent bilayer pairs.
Extensive vesicle fusion accompanies 4 - 5 hours drying of both 5 and 10% DMSO-treated samples. No fusion was observed in the 25% DMSO-treated sample after 4-5 hours drying and individual vesicles remained round as in the 2-2½ hour samples of all treatments. Overnight drying also causes extended sheets of bilayer pairs to form in the 5% DMSO-treated samples but, with 10 and 25% treated vesicles, destroys the double bilayers and only occasional dense regions of membrane whorls remain. Both EG and DMSO promote more rapid fusion of FSR vesicles than does glycerol but overnight drying after treatment with 10 or 25% DMSO destroys the fused membrane.
