EFFECT OF TEMPERATURE ON RELAXATION RATE AND CA2+, MG2+ DISSOCIATION RATES FROM PARVALBUMIN OF FROG-MUSCLE FIBERS
EFFECT OF TEMPERATURE ON RELAXATION RATE AND CA2+, MG2+ DISSOCIATION RATES FROM PARVALBUMIN OF FROG-MUSCLE FIBERS
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DOI：
10.1113/jphysiol.1992.sp019092
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发表时间：
1992-04-01
影响因子：
5.5
通讯作者：
RALL, JA
中科院分区：
文献类型：
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作者：
HOU, TT;JOHNSON, JD;RALL, JA
1. 温度对松弛率的影响（作为等长破伤风持续时间的函数）以及对纯化小白蛋白（PA）的Ca2+和Mg2+解离率的影响进行了研究，以验证PA促进蛙骨骼肌松弛的假设。采用颞蛙骨骼肌单纤维和PA IVB。相对于松弛速率的最终稳定值，松弛速率随破伤风持续时间的增加而减慢的幅度在0℃时比在10℃时大3倍。在0 ~ 10℃范围内，随着破伤风持续时间的增加，松弛率的Q10从2.3增加到3.7。Ca2+和Mg2+在PA中解离的速率常数为1.03 +/- 0.03 s-1（平均+/- S.D, n = 5）和3.42 +/- 0.14 s-1 (n = 5)， Q10值在0-20℃范围内分别为2.3和1.9。松弛率随破伤风持续时间的增加而减慢，松弛率随休息而恢复，在10℃下延长破伤风后的时间过程与先前报道的0℃下Mg2+和Ca2+从PA分离的速率相似。松弛速率减缓的相对幅度的温度依赖性和松弛速率的Q10随破伤风持续时间的增加而增加，可以解释为松弛期间肌浆网摄取Ca2+的Q10大于PA吸收Ca2+的Q10。将PA在不同温度下的Ca2+和Mg2+解离率与PA功能的其他指标进行比较，得出PA在0-20℃范围内促进蛙骨骼肌松弛的结论。
1. Influence of temperature on relaxation rate as a function of isometric tetanus duration and on Ca2+ and Mg2+ dissociation rates from purified parvalbumin (PA) was examined to test the hypothesis that PA promotes relaxation in frog skeletal muscle. Single fibres and PA IVB from Rana temporaria skeletal muscle were utilized.2. The magnitude of slowing of relaxation rate with increasing tetanus duration, relative to the final, steady value of relaxation rate, is 3-fold greater at 0 than at 10-degrees-C.3. In the 0-10-degrees-C range, the Q10 for relaxation rate increases from 2.3 to 3.7 with increasing tetanus duration.4. Dissociation of Ca2+ and Mg2+ from PA exhibited: (i) rate constants of 1.03 +/- 0.03 s-1 (mean +/- S.D., n = 5) and 3.42 +/- 0.14 s-1 (n = 5) at 20-degrees-C and (ii) Q10 values of 2.3 and 1.9 in the 0-20-degrees-C range, respectively.5. Time courses of slowing of relaxation rate with increasing tetanus duration and recovery of relaxation rate with rest after a prolonged tetanus at 10-degrees-C are similar to rates of dissociation of Mg2+ and Ca2+ from PA, respectively, as previously reported at 0-degrees-C.6. Both the temperature dependence of the relative magnitude of slowing of relaxation rate and the increased Q10 of relaxation rate with increased tetanus duration can be explained if the Q10 for Ca2+ uptake by the sarcoplasmic reticulum is greater than the Q10 for Ca2+ sequestration by PA during relaxation. When Ca2+ and Mg2+ dissociation rates from PA at various temperatures are compared to other proposed indicators of PA function, it is concluded that PA facilitates relaxation of frog skeletal muscle in the 0-20-degrees-C range.