カエル腹直筋に対するAcetylcholineの作用
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概要
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In the present paper, studies on the contraction caused by the administration of acetyicholine (Ach) in M. rectus abdominis of frog were reported. When this muscle was immersed' in the Ach. solution of various concentrations, it contracted rapidly at first, then reached to its maximal height, which was held as long as the action of Ach. was maintained. The muscle began to relax only when Ach. was washed off with Ringer's solution. for lnog time.<BR>The maximal contraction height was proportional to the logarithm of Ach. concentration which acted on the muscle. The following formula was valid for the present experimental results.<BR>h=Klog C+K'<BR>Where h means the contraction height, C is the concentration of Ach. applied. K and K' are some constants.<BR>Ach. contraction was accompanied by the repetitive spike potentials for a short period, which soon disappeared notwithstanding the contraction was still maintained. Such was the case also in the Ach. contraction of the sartorius muscle.<BR>From these facts, the present authors concluded that the Ach. contraction is consisted from two components, ie, one is the tetanus which accompanies the repetitive spike potentials, and the other is the contracture of non-conductive nature.<BR>The authors could prove experimentally that the tetanic component was evoked by the action of Ach. on the endplate, and the contracture component was caused by the direct action of Ach. on the muscle fibre itself. Ach. contraction of the sartorius muscle differs somewhat from that of the M. rectus abd. The latter is predominant in the contracture component rather than the former.<BR>The measurement of cholinesterase elucidated that the M. rectus abd. contains this ferment far less than the sartorius muscle. The authors are of the opinion that the difference of the Ach. contraction of both kinds of the muscles is caused by the different contents of cholinesterase. It is well known that the height of the Ach. contraction in M. rectus abd. of frog can be utilized for the measurement of Ach, concentration. In this case the contraction height, used as the indicator, is due to the contracture component, but not to the tetanic.
- 学校法人 昭和大学・昭和医学会の論文