二氧化碳分压、pH值及细胞外钙对大鼠气道平滑肌收缩的影响。

Effects of PCO2, pH and extracellular calcium on contraction of airway smooth muscle from rats.

作者信息

Twort C H, Cameron I R

出版信息

Respir Physiol. 1986 Dec;66(3):259-67. doi: 10.1016/0034-5687(86)90078-2.

Abstract

The effect of changes in PCO2 on airway smooth muscle was studied in acetylcholine-induced contractions of isolated rat trachea. Elevation of superfusate PCO2 from control PCO2, 38 mm Hg (pH 7.49), to 168 mm Hg (pH 6.74) decreased tension to 68% of control tension; reduction of PCO2 to 19 mm Hg (pH 7.84) increased tension to 104%. Similar effects on tension occurred when pH was altered by varying superfusate bicarbonate concentration at constant PCO2. Modification of the response to changes in PCO2 by varying extracellular calcium (Ca2+) concentration and also by verapamil indicated that changes in PCO2 and pH may alter Ca2+ uptake by the smooth muscle. Calcium uptake was measured by 45Ca2+ and the lanthanum method. At control pH 7.49, net Ca2+ uptake was 5.34 mmol Ca2+/kg trachea 60 min after the onset of contraction; this decreased to 4.26 at pH 6.88, and increased to 6.58 at pH 7.85. The results suggest that the mechanism whereby changes in PCO2 affect airway smooth muscle contraction is a pH-dependent alteration of Ca2+ uptake.

摘要

在乙酰胆碱诱导的离体大鼠气管收缩实验中，研究了二氧化碳分压（PCO2）变化对气道平滑肌的影响。将灌流液的PCO2从对照值38 mmHg（pH 7.49）升高至168 mmHg（pH 6.74），可使张力降至对照张力的68%；将PCO2降至19 mmHg（pH 7.84），则使张力升高至104%。在PCO2恒定的情况下，通过改变灌流液碳酸氢盐浓度来改变pH时，对张力产生了类似的影响。通过改变细胞外钙（Ca2+）浓度以及使用维拉帕米来改变对PCO2变化的反应，表明PCO2和pH的变化可能会改变平滑肌对Ca2+的摄取。采用45Ca2+和镧法测量钙摄取。在对照pH 7.49时，收缩开始60分钟后，气管组织的净Ca2+摄取量为5.34 mmol Ca2+/kg；在pH 6.88时降至4.26，在pH 7.85时升至6.58。结果表明，PCO2变化影响气道平滑肌收缩的机制是Ca2+摄取的pH依赖性改变。