Mitochondrial regulation of the cytosolic Ca<SUP>2+</SUP> concentration and the Ins<i>P</i>₃-sensitive Ca<SUP>2+</SUP> store in guinea-pig colonic smooth muscle

作     者：McCarron, JG Muir, TC 

作者机构：Univ Glasgow Inst Biomed & Life Sci Neurosci & Biomed Syst Glasgow G12 8QQ Lanark Scotland 

出 版 物：《JOURNAL OF PHYSIOLOGY-LONDON》 (生理学杂志)

年 卷 期：1999年第516卷第1期

页      面：149-161页

核心收录：

学科分类：0710[理学-生物学] 1001[医学-基础医学(可授医学、理学学位)] 07[理学] 071003[理学-生理学] 

基　　金：Wellcome Trust Funding Source: Medline 

主　　题：腺苷三磷酸酶类/药理学 抗代谢药/药理学 钙/代谢 碳酰氰化物间-氯苯基腙/药理学 结肠/药物作用 结肠/代谢 结肠/超微结构 胞质溶胶/药物作用 胞质溶胶/代谢 胞质溶胶/超微结构 酶抑制剂/药理学 荧光染料/诊断应用 杂环化合物 3环 肌醇1 4 5-三磷酸/药理学 离子载体/药理学 膜电位/生理学 线粒体 肌/代谢 肌 平滑/药物作用 肌 平滑/代谢 肌 平滑/超微结构 寡霉素类/药理学 膜片钳术 毒胡萝卜内酯/药理学 动物 豚鼠 男(雄)性 

摘      要：1. Mitochondrial regulation of the cytosolic Ca2+ concentration ([Ca2+](c)) in guinea-pig single colonic myocytes has been examined, using whole-cell recording, flash photolysis of caged InsP(3) and microfluorimetry. 2. Depolarization increased [Ca2+](c) and triggered contraction. Resting [Ca2+](c) was virtually restored some 4 s after the end of depolarization, a time when the muscle had shortened to 50% of its fully relaxed length. The muscle then slowly relaxed (t(1/2) = 17 s). 3. The decline in the Ca2+ transient was monophasic but often undershot or overshot resting levels, depending on resting [Ca2+](c). The extent of the overshoot or undershoot increased when increasmg peak [Ca2+](c). 4. Carbonyl cyanide m-chlorophenyl hydrazone (CCCP;5 mu M), which dissipates the mitochondrial proton electrochemical gradient and therefore prevents mitochondrial Ca2+ accumulation, slowed Ca2+ removal at high ( 300 nM) but not at lower [Ca2+](c) and abolished [Ca2+](c) overshoots. Oligomycin B (5 mu M), which prevents mitchondrial ATP production, affected neither the rate of decline nor the magnitude of the overshoot. 5. During depolarization, the global rhod-2 signal (which represents the mitochondrial matrix Ca2+ concentration, [Ca2+](m)) rose slowly in a CCCP-sensitive manner during and for about 3 s after depolarization had ended. [Ca2+](m) then slowly decreased over tens of seconds. 6. Inhibition of sarcoplasmic reticulum Ca2+ uptake with thapsigargin (100 nM) reduced the undershoot and increased the overshoot. 7. Flash photolysis of caged InsP(3) (20 mu M) evoked reproducible increases in [Ca2+](c). CCCP (5 mu M) reduced the magnitude of the [Ca2+](c) transients evoked by flash photolysis of caged InsP(3). Oligomycin B (5 mu M) did not reduce the inhibition of the InsP(3)-induced Ca2+ transient by CCCP thus minimizing the possibility that CCCP lowered ATP levels by reversing the mitochondrial ATP synthase and so reducing SR Ca2+ refilling. 8. While CCCP reduced the magn