关于牛蛙骨骼肌收缩持续时间影响的磷核磁共振研究。

Phosphorus nuclear magnetic resonance studies on the effect of duration of contraction in bull-frog skeletal muscles.

作者信息

Kawano Y, Tanokura M, Yamada K

机构信息

Department of Physiology, Medical College of Oita, Japan.

出版信息

J Physiol. 1988 Dec;407:243-61. doi: 10.1113/jphysiol.1988.sp017413.

DOI:10.1113/jphysiol.1988.sp017413

PMID:3267189

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1191201/

Abstract

Contraction and recovery of bull-frog skeletal muscles were studied using 31P nuclear magnetic resonance (NMR), with a time resolution of 16 s, at 4 degrees C. The muscles were stimulated tetanically for various periods (0.2-10 s) at a sarcomere length of 2.4 microns. Changes in the concentrations of inorganic phosphate (Pi), phosphocreatine (PCr) and other metabolites were studied for repeated cycles of contraction and recovery. 2. In resting muscles, bathed in a solution gassed with 95% O2 and 5% CO2, the concentration of Pi was 1.15 +/- 0.21 mmol kg-1 wet weight (mean +/- one S.D., n = 12), that of ATP was 3.32 +/- 0.15 mmol kg-1 (mean +/- one S.D., n = 12) and that of sugar phosphates was less than 0.5 mmol kg-1. The intracellular pH (pHi) was 7.22 +/- 0.01 (mean +/- one S.D., n = 12). These results are averages for fibres which probably have different values. 3. On stimulating the muscles pHi shifted in the alkaline direction and subsequently recovered. The extent of the alkaline shift was linearly related to the contraction duration (0.2-10 s) with a rate of 0.01 pH unit s-1. 4. The increase in Pi with stimulus duration was biphasic, consisting of an early burst, 0.38 +/- 0.10 mmol kg-1 (+/- 1 S.D., n = 5), complete within about 0.2-0.5 s, followed by a slower steady-state increase. The steady-state rate of Pi increase was 0.33 +/- 0.02 mmol kg-1 s-1 (+/- 1 S.D., n = 5) in agreement with the results of previous studies involving chemical analyses. 5. The time course of Pi recovery was well described by a single exponential. Intensities of ATP, sugar phosphates and the peaks in the phosphodiester region did not change during a 2 s tetanus. 6. The amount of PCr hydrolysed (-delta PCr), associated with contractions of various durations, coincided well with Pi increase (delta Pi). This was found during the whole recovery period except for the initial few minutes following relaxation when -delta PCr was significantly smaller than delta Pi. The difference was 0.35 +/- 0.03 mmol kg-1 (mean +/- 1 S.D., n = 3) immediately after a 2 s tetanus. 7. In contractions of 2 s or longer, the extent of the temporal separation between delta Pi and -delta PCr was almost the same, but in contractions of less than 2 s it was significantly reduced.(ABSTRACT TRUNCATED AT 400 WORDS)

摘要

采用磷-31核磁共振（NMR）技术，在4℃下，以16秒的时间分辨率，对牛蛙骨骼肌的收缩和恢复过程进行了研究。在肌节长度为2.4微米的条件下，对肌肉进行不同时长（0.2 - 10秒）的强直刺激。研究了无机磷酸盐（Pi）、磷酸肌酸（PCr）及其他代谢物浓度在收缩和恢复的重复周期中的变化。2. 在用95% O₂和5% CO₂混合气体通气的溶液中浸泡的静息肌肉中，Pi的浓度为1.15±0.21 mmol·kg⁻¹湿重（平均值±标准差，n = 12），ATP的浓度为3.32±0.15 mmol·kg⁻¹（平均值±标准差，n = 12），糖磷酸盐的浓度小于0.5 mmol·kg⁻¹。细胞内pH值（pHi）为7.22±0.01（平均值±标准差，n = 12）。这些结果是可能具有不同值的纤维的平均值。3. 刺激肌肉时，pHi向碱性方向移动，随后恢复。碱性移动的程度与收缩持续时间（0.2 - 10秒）呈线性关系，速率为0.01 pH单位·秒⁻¹。4. 随着刺激持续时间的增加，Pi的增加呈双相性，包括一个早期爆发，约0.38±0.10 mmol·kg⁻¹（±1标准差，n = 5），在约0.2 - 0.5秒内完成，随后是较慢的稳态增加。Pi增加的稳态速率为0.33±0.02 mmol·kg⁻¹·秒⁻¹（±1标准差，n = 5），与先前涉及化学分析的研究结果一致。5. Pi恢复的时间进程可用单指数很好地描述。在2秒强直收缩期间，ATP、糖磷酸盐的强度以及磷酸二酯区域的峰没有变化。6. 与不同持续时间收缩相关的PCr水解量（-ΔPCr）与Pi增加量（ΔPi）非常吻合。在整个恢复期间都发现了这一点，但在放松后的最初几分钟除外，此时-ΔPCr明显小于ΔPi。在2秒强直收缩后立即测量，差异为0.35±0.03 mmol·kg⁻¹（平均值±1标准差，n = 3）。7. 在2秒或更长时间的收缩中，ΔPi和-ΔPCr之间的时间间隔程度几乎相同，但在小于2秒的收缩中，该间隔明显减小。（摘要截短至400字）