Measurements of Ultrasonic Velocity of Erythrocyte Ghosts in Suspension with Sing-Around Method

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An apparatus utilizing a sing-around method was constructed consisting of a pulse generator, a sample holder with transducers and a Schmitt circuit, in which ultrasonic velocity was determined from the period of pulses by an electronic counter with a relative accuracy of 10^<-6>. The velocity V and the denisty p were measured for suspensions of bovine erythrocyte ghosts in 150 mM NaCl at pH 7.0 as the temperature was varied from 20° to 40℃ and the concentration c was varied from 1 to 8 mg in weights of dry membrane per 1 cm^3. An abrupt change was observed in V and p between 31° and 33℃, which was considered as a transition from a crystalline to liquid-like structure in lipid hydrocarbon chains of the membrane. The density and the bulk modulus of the membrane were estimated from the limiting numbers of the density [p] and the velocity [V], where [p]=<lim>___<c→0>(p-p_0)/p_0c, [V]=<lim>___<c→0>(V-V_0)/V_0c and the subscript 0 denotes the medium.
社団法人応用物理学会の論文
1975-03-05