Relationship between intracellular PO2 recovery kinetics and fatigability in isolated single frog myocytes.
Relationship between intracellular PO2 recovery kinetics and fatigability in isolated single frog myocytes.
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分离的单个青蛙肌细胞内 PO2 恢复动力学与疲劳性之间的关系。
DOI：
10.1152/japplphysiol.00355.2004
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Hogan,MichaelC
中科院分区：
文献类型：
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作者：
Kindig,CaseyA;Walsh,Brandon;Howlett,RichardA;Stary,CreedM;Hogan,MichaelC
在单个青蛙骨骼肌细胞中，“疲劳性”和氧化能力之间存在线性关系。本研究的目的是研究单个非洲爪蟾（Xenopus laevismyocytes）心肌细胞内氧分压（PiO_2）补偿动力学与疲劳性之间的关系，以验证PiO_2补偿动力学与心肌细胞疲劳性线性相关的假设，并由此推断，与心肌细胞的氧化能力线性相关。从蚓状肌中分离的单个肌细胞（n= 30）在0.25或0.33 Hz频率下进行2 min等长峰强直收缩，同时通过磷光猝灭技术连续测量PiO 2。计算PiO 2从收缩值恢复至静息基线的平均反应时间（MRT;至总反应63%的时间）。在最初的方波恒定频率收缩试验之后，每个细胞进行增量收缩方案[即，频率从0.167、0.25、0.33、0.5、1.0和2.0 Hz每2 min增加一次，直至峰值张力降至初始值的50%以下（TTF）]。肌细胞的TTF值范围为3.39 - 10.04 min。PiO 2恢复MRT范围为26 - 146 s。TTF与PiO 2恢复MRT之间存在显著（P< 0.05）负相关（MRT =-12.68TTF +168.3，r2 = 0.605）。这些数据表明疲劳性和氧化磷酸化恢复动力学之间的显着相关性，这与氧化能力部分决定骨骼肌能量恢复代谢需求改变的速度的概念一致。
In single frog skeletal myocytes, a linear relationship exists between “fatigability” and oxidative capacity. The purpose of this investigation was to study the relationship between the intracellular Po2(PiO2) offset kinetics and fatigability in singleXenopus laevismyocytes to test the hypothesis that PiO2offset kinetics would be related linearly with myocyte fatigability and, by inference, oxidative capacity. Individual myocytes (n= 30) isolated from lumbrical muscle were subjected to a 2-min bout of isometric peak tetanic contractions at either 0.25- or 0.33-Hz frequency while PiO2was measured continuously via phosphorescence quenching techniques. The mean response time (MRT; time to 63% of the overall response) for PiO2recovery from contracting values to resting baseline was calculated. After the initial square-wave constant-frequency contraction trial, each cell performed an incremental contraction protocol [i.e., frequency increase every 2 min from 0.167, 0.25, 0.33, 0.5, 1.0, and 2.0 Hz until peak tension fell below 50% of initial values (TTF)]. TTF values ranged from 3.39 to 10.04 min for the myocytes. The PiO2recovery MRT ranged from 26 to 146 s. A significant (P< 0.05), negative relationship (MRT = −12.68TTF + 168.3,r2= 0.605) between TTF and PiO2recovery MRT existed. These data demonstrate a significant correlation between fatigability and oxidative phosphorylation recovery kinetics consistent with the notion that oxidative capacity determines, in part, the speed with which skeletal muscle can recover energetically to alterations in metabolic demand.