量热法证明高渗介质中幼鼠骨骼肌钠氢交换被激活。

Evidence by calorimetry for an activation of sodium-hydrogen exchange of young rat skeletal muscle in hypertonic media.

作者信息

Chinet A, Giovannini P

机构信息

Department of Physiology, Centre Médical Universitaire, Geneva, Switzerland.

出版信息

J Physiol. 1989 Aug;415:409-22. doi: 10.1113/jphysiol.1989.sp017728.

DOI:10.1113/jphysiol.1989.sp017728

PMID:2640465

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1189183/

Abstract

The rate of energy dissipation associated with Na(+)-H+ exchange in isolated, superfused soleus muscles from young rats was measured with an isothermal microcalorimeter during quasi-stationary states of oxidative metabolism. 2. Under normal physiological conditions, amiloride, an inhibitor of the Na(+)-H+ exchange across plasma membranes, had no measurable effect on the specific rate of muscle heat production (E); the ouabain-suppressible part of E was identical whether amiloride was absent or present. 3. E was increased under hyperosmotic conditions and the difference with respect to control (excess E) was proportional to the degree of hyperosmolarity of the superfusate. It was 48% of basal E during a +100 mosM stress (with no change of extracellular Na+ concentration, Na+o). Inhibition of Ca2+ release into the sarcoplasm with sodium dantrolene (10(-5) M) or tetracaine (5 x 10(-5) M) suppressed a substantial part (65 and 53%, respectively) of the steady-state excess E (1.2 mW (g wet weight)-1) induced by the +100 mosM stress. Practically 100% of excess E was suppressed in the nominal absence of extracellular sodium (Na+o = 0, Li+ substitution) or under 15 mM-Na+o, and excess E was enhanced when Na+o was increased (hyperosomolarity by addition of Na2SO4 instead of sucrose). 4. Under hyperosmotic conditions, amiloride at the 5 x 10(-7) M concentration had no effect on excess E whereas at 10(-4) M it induced a significant decrease of excess E. The absolute effect of 10(-4) M-amiloride was -0.34 mW (g wet weight)-1 (equal to 28% of the excess E due to a +100 mosM-sucrose stress and to 14% of the excess E due to a +100 mosM-Na2SO4 stress). It was left unaltered in the presence of dantrolene and was independent of the way the +100 mosM stress was obtained (i.e. 100 mM-sucrose or 50 mM-Na2SO4). It was suppressed at Na+o = 0-15 mM and could be mimicked by guanochlor, another potent inhibitor of Na(+)-H+ exchange. In the presence of 10(-4) M-amiloride, the ouabain-suppressible E was significantly reduced. In the presence of ouabain, amiloride had no effect. 5. Muscle tissue space available to [3H]inulin was measured in parallel experiments. It was 23.3% under control conditions and 30.6% after a 2 h exposure of the muscle to a +100 mosM-Na2SO4 stress.(ABSTRACT TRUNCATED AT 400 WORDS)

摘要

在年轻大鼠分离的、经超灌注的比目鱼肌中，于氧化代谢的准稳态期间，用等温微量热计测量了与钠氢交换相关的能量耗散速率。2. 在正常生理条件下，氨氯吡脒（一种跨质膜钠氢交换的抑制剂）对肌肉产热的比速率（E）没有可测量的影响；无论有无氨氯吡脒，E中哇巴因可抑制的部分是相同的。3. 在高渗条件下E增加，相对于对照的差异（过量E）与超灌注液的高渗程度成正比。在 +100 mosM 应激期间（细胞外钠浓度Na⁺ₒ无变化），它是基础E的48%。用丹曲林钠（10⁻⁵ M）或丁卡因（5×10⁻⁵ M）抑制钙离子释放到肌浆中，分别抑制了由 +100 mosM 应激诱导的稳态过量E（1.2 mW（克湿重）⁻¹）的很大一部分（分别为65%和53%）。在名义上无细胞外钠（Na⁺ₒ = 0，锂替代）或15 mM - Na⁺ₒ 时，几乎100%的过量E被抑制，当Na⁺ₒ 增加时（通过添加硫酸钠而非蔗糖产生高渗）过量E增强。4. 在高渗条件下，5×10⁻⁷ M 浓度的氨氯吡脒对过量E无影响，而在10⁻⁴ M 时它导致过量E显著降低。10⁻⁴ M - 氨氯吡脒的绝对效应为 -0.34 mW（克湿重）⁻¹（相当于因 +100 mosM - 蔗糖应激导致的过量E的28%，以及因 +100 mosM - 硫酸钠应激导致的过量E的14%）。在丹曲林存在时其不变，且与获得 +100 mosM 应激的方式无关（即100 mM - 蔗糖或50 mM - 硫酸钠）。在Na⁺ₒ = 0 - 15 mM时它被抑制，并且可被鸟嘌呤氯仿（另一种有效的钠氢交换抑制剂）模拟。在存在10⁻⁴ M - 氨氯吡脒时，哇巴因可抑制的E显著降低。在存在哇巴因时，氨氯吡脒无影响。5. 在平行实验中测量了对[³H]菊粉可用的肌肉组织间隙。对照条件下为23.3%，肌肉暴露于 +100 mosM - 硫酸钠应激2小时后为30.6%。