アブストラクト(22巻1号:神奈川歯学)

神奈川歯学

Japanese

Title : 咬筋小胞体におけるCalcium動態- 大腿筋, 心筋との比較と温度依存性 -
Subtitle : 原著
Authors : 加藤康, 伊藤春生
Authors(kana) :
Organization : 神奈川歯科大学歯科薬理学教室
Journal : 神奈川歯学
Volume : 22
Number : 1
Page : 1-12
Year/Month : 1987 / 6
Article : 原著
Publisher : 神奈川歯科大学学会
Abstract : 「緒言」骨格筋小胞体(SR)は, 筋原線維をとりまく小管状の構造物で, もっぱらcalciumの輸送と貯蔵を行う. SRに貯えられたcalciumは筋線維の興奮に際し筋形質に放出されtroponinと結合して筋線維の収縮をひき起こすが, 放出されたcalciumは再びSR内に取り込まれる. この取り込みによって筋原線維周辺のcalcium濃度が低下し, troponinからcalciumが解離して筋弛緩が起こる. SRによるcalciumの取り込みはATP加水分解に共役した能動輸送であるが, このcalcium輸送を担うのがSR膜に存在するcalcium-stimulated, magnesium-dependent ATPase (calcium-ATPase)である. このcalcium-ATPaseの含量において, 骨格筋SRと心筋SRで相違がみられるが, 反応機構やcalcium輸送との共役機構は両者ともに基本的には類似している.
Practice : 歯科学
Keywords : 咬筋小胞体, カルシウム, 温度依存性

English

Title : Calcium Kinetics in Sarcoplasmic Reticulum of Canine Masseter Muscle - Comparison of Temperature Dependence in Masseter Muscle, Femoral Muscle and Heart Muscle -
Subtitle :
Authors : Yasushi KATO, Haruo Ito
Authors(kana) :
Organization : Department of Pharmacology, Kanagawa Dental College
Journal : Kanagawa Shigaku
Volume : 22
Number : 1
Page : 1-12
Year/Month : 1987 / 6
Article : Original article
Publisher : Kanagawa Odontological Society
Abstract : [Abstract]: Steady-state calcium uptake and difusional passive calcium efflux from sarcoplasmic reticulum (SR) vesicles isolated from canine masseter muscle, femoral muscle and heart muscle were determined by measuring net efflux of calcium after stopping pump-mediated fluxes. The order of the total amount of calcium (Cat) associated with the SR was masseter muscle > femoral muscle > heart muscle at low temperature (10℃-20℃) and femoral muscle > masseter muscle > heart muscle at high temperature (20℃-40℃) ; and of total intravesicular calcium (Cat-Cabo) was masseter muscle = femoral muscle > heart muscle at low temperature and femoral muscle > masseter muscle > heart muscle at high temperature. The temperature dependency of SR Cat-Cabo in femoral muscle was similar to that in heart muscle. Cat-Cabo of masseter muscle SR, however, was rapidly decreased at high temperature in the range 25℃-40℃. The increase in the apparent calcium permeability (K/v) of SR from masseter muscle, calculated as the passive calcium efflux (Jp) divided by the Cat-Cabo, was more promoted than that of SR from femoral muscle or heart muscle between 25℃ and 40℃. However, there was no difference in temperature dependence of Jp between masseter muscle and femoral muscle. An explanation for this can be ascertained from the free calcium load, Cai, on which Jp is dependent. Since SR Cai of masseter muscle may markedly leak out as temperature elevates, K/v increases in a temperature-dependent manner, over the temperature range of 25℃-40℃ ; thus there was no difference in Jp between masseter muscle and femoral muscle. The first order rate constant for masseter muscle SR had a complicated dependence on temperature ; K/v changed little from 15℃ to 20℃ and then sharply increased from 20℃ to 35℃. The calcium-ATPase showed a slight break at 22.5℃. Furthermore, K/v was unaffected by Mg concentration. The results suggest that SR from masseter muscle has greater capability of calcium release than that from femoral muscle or heart muscle, the passive calcium efflux is not carrier mediated, and passive calcium efflux is not a likely route of calcium release during excitation-contraction coupling.
Practice : Dentistry
Keywords :