Lakin-Thomas P L, Brand M D
Department of Biochemistry, University of Cambridge, U.K.
Biochem J. 1988 Nov 15;256(1):167-73. doi: 10.1042/bj2560167.
The role of calcium in the control of respiration by the mitogen concanavalin A (ConA) was investigated in rat thymocytes. ConA induced an increase in both mitochondrial respiration and the mitochondrial calcium pool. The stimulation of respiration was shown to be independent of the increase in mitochondrial calcium: the calcium pool declined after 3 min, whereas the respiration increase was persistent, and was not affected by depletion of the calcium pool or by buffering intracellular Ca2+ transients with quin2. The mitogen phytohaemagglutinin stimulated respiration to the same extent as ConA, but did not increase the mitochondrial calcium pool. In addition, respiration was unaffected by changes in the mitochondrial calcium pool induced by increasing or decreasing extracellular calcium. These results indicate that control of respiration is not located in the Ca2+-sensitive mitochondrial dehydrogenases. The ConA-induced increase in respiration could be blocked by oligomycin, suggesting control by cytoplasmic ATP turnover, and was not associated with detectable changes in NAD(P)H fluorescence, indicating a balance between increased electron transfer and increased supply of reduced substrates.
在大鼠胸腺细胞中研究了钙在有丝分裂原伴刀豆球蛋白A（ConA）对呼吸的调控中的作用。ConA可诱导线粒体呼吸和线粒体钙库增加。结果表明，呼吸的刺激与线粒体钙的增加无关：3分钟后钙库下降，而呼吸增加持续存在，且不受钙库耗竭或用喹啉2缓冲细胞内Ca2+瞬变的影响。有丝分裂原植物血凝素刺激呼吸的程度与ConA相同，但不会增加线粒体钙库。此外，呼吸不受细胞外钙增加或减少所诱导的线粒体钙库变化的影响。这些结果表明，呼吸的调控并不位于对Ca2+敏感的线粒体脱氢酶中。ConA诱导的呼吸增加可被寡霉素阻断，提示受细胞质ATP周转的调控，且与NAD(P)H荧光的可检测变化无关，表明电子传递增加与还原底物供应增加之间达到平衡。
