小龙虾肌肉中线粒体解偶联剂诱导的细胞内pH值下降和静息张力增加。

Fall in intracellular pH and increase in resting tension induced by a mitochondrial uncoupling agent in crayfish muscle.

作者信息

Kaila K, Mattsson K, Voipio J

机构信息

Department of Zoology, University of Helsinki, Finland.

出版信息

J Physiol. 1989 Jan;408:271-93. doi: 10.1113/jphysiol.1989.sp017459.

DOI:10.1113/jphysiol.1989.sp017459

PMID:2778730

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1190403/

Abstract

The influence of the mitochondrial uncoupling agent carbonylcyanide-m-chlorophenylhydrazone (CCCP) upon resting tension and intracellular pH (pHi) was studied in the dactyl opener muscle of the crayfish. pHi was measured with liquid sensor H+-selective microelectrodes. 2. CCCP (10(-6)-10(-5) mol l-1) induced a reversible, tonic contracture which was associated with a depolarization of the membrane potential. Both effects were augmented by a fall and inhibited by a rise in extracellular pH. The action of CCCP on tension was not mimicked by cyanide + oligomycin or by cyanide + dicyclohexylcarbodiimide nor was it inhibited by pre-exposure to these agents. 3. CCCP produced an initial alkalosis of less than 0.1 units and thereafter a fall in pHi of 0.4-0.6 units during which the sarcolemmal H+ driving force decreased from 61 to 15 mV. The apparent influx of H+ due to CCCP had a maximum of 2.7 mequiv l-1 min-1. The CCCP-induced acidosis was unaffected by iodacetate (0.5 mmol l-1) but it was inhibited by a depolarization of the membrane potential. 4. The contraction caused by CCCP was not due to the simultaneous fall in pHi since an intracellular acidosis of equal magnitude, produced by propionate (50 mmol l-1), did not lead to force generation. In addition, propionate had an inhibitory effect on the depolarization and contracture caused by CCCP. 5. Both the depolarization and the contracture caused by CCCP were inhibited by gamma-aminobutyric acid (GABA). The contracture was blocked by Cd2+, Mn2+ and by a nominally Ca2+ -free medium but not by a pre-exposure to caffeine (20 mmol l-1). Cd2+ and Mn2+ had no influence on the fall of pHi caused by CCCP. 6. It is concluded that CCCP induces a sarcolemmal H+ conductance which leads to a fall in pHi and to a depolarization of the membrane potential. This depolarization activates sarcolemmal, voltage-dependent calcium channels and thereby induces an increase in tension. The initial alkalosis produced by CCCP may be due to a transient uptake of H+ by mitochondria.

摘要

研究了线粒体解偶联剂羰基氰化物-间氯苯腙（CCCP）对小龙虾开指肌静息张力和细胞内pH（pHi）的影响。用液体传感器H⁺选择性微电极测量pHi。2. CCCP（10⁻⁶ - 10⁻⁵ mol l⁻¹）诱导可逆的强直性挛缩，这与膜电位的去极化有关。细胞外pH下降会增强这两种效应，而细胞外pH上升则会抑制它们。氰化物 + 寡霉素或氰化物 + 二环己基碳二亚胺不会模拟CCCP对张力的作用，预先暴露于这些试剂也不会抑制CCCP的作用。3. CCCP最初产生小于0.1个单位的碱中毒，此后pHi下降0.4 - 0.6个单位，在此期间肌膜H⁺驱动力从61 mV降至15 mV。CCCP引起的H⁺表观内流最大值为2.7 mequiv l⁻¹ min⁻¹。碘乙酸盐（0.5 mmol l⁻¹）不影响CCCP诱导的酸中毒，但膜电位去极化会抑制它。4. CCCP引起的收缩不是由于pHi同时下降，因为丙酸盐（50 mmol l⁻¹）产生的同等程度的细胞内酸中毒不会导致力的产生。此外，丙酸盐对CCCP引起的去极化和挛缩有抑制作用。5. CCCP引起的去极化和挛缩都受到γ-氨基丁酸（GABA）的抑制。挛缩被Cd²⁺、Mn²⁺和名义上无Ca²⁺的培养基阻断，但预先暴露于咖啡因（20 mmol l⁻¹）则不会。Cd²⁺和Mn²⁺对CCCP引起的pHi下降没有影响。6. 得出的结论是，CCCP诱导肌膜H⁺电导，导致pHi下降和膜电位去极化。这种去极化激活肌膜电压依赖性钙通道，从而诱导张力增加。CCCP产生的初始碱中毒可能是由于线粒体对H⁺的短暂摄取。