Substrate dependence and oxygen sensitivity of tone and of spontaneous and evoked contractions of the distal colonic muscularis mucosae of opossum.
Substrate dependence and oxygen sensitivity of tone and of spontaneous and evoked contractions of the distal colonic muscularis mucosae of opossum.
复制标题
负鼠远端结肠粘膜肌层的音调以及自发和诱发收缩的基质依赖性和氧敏感性。
DOI：
10.1016/0016-5085(86)90624-4
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发表时间：
1986
期刊：
影响因子：
29.4
通讯作者：
Christensen,J
中科院分区：
文献类型：
--
作者：
Percy,WH;Roberts,RL;Mason,JB;Christensen,J
负鼠远端结肠粘膜肌层在体外无氧环境中不能维持张力和产生自发性收缩。为了进一步研究这一现象，在不同氧浓度下检测了对激动剂的剂量反应曲线。在其他实验中，组织被主动耗尽（即，在无底物的环境中反复刺激，直到观察不到对K+、乙酰胆碱或组胺的反应），然后用替代底物平衡3小时，此时重新评价组织对激动剂收缩的能力。减少可用的氧气取消音调，并造成了分级损失的反应组胺;相反，在0%的氧气最大反应乙酰胆碱减少了75%。取消的语气中加入氰化物的沐浴介质并没有影响的幅度组胺和乙酰胆碱的反应。该组织能够在不同程度上使用所有选择的替代底物进行乙酰胆碱诱导的收缩;同样，除了β-羟基丁酸酯外，它可以在一定程度上使用所有底物来支持对组胺的反应。证据表明，维持张力所需的能量来源与维持K+或激动剂诱导的收缩所需的能量来源不同，并且等张收缩对外源性底物的依赖性随药理学刺激而变化。
The muscularis mucosae of the opossum distal colon fails to maintain tone and to generate spontaneous contractions in an anaerobic environment in vitro. To investigate this phenomenon further, doseresponse curves to agonists under different oxygen concentrations were examined. In other experiments the tissue was actively exhausted (i.e., repeatedly stimulated in a substrate-free environment until no response to K+, acetylcholine, or histamine could be observed) and then equilibrated with an alternative substrate for 3 h, when the ability of the tissue to contract to agonists was reevaluated. Reducing the available oxygen abolished tone and caused a graded loss of responses to histamine; in contrast, at 0% oxygen maximum responses to acetylcholine were reduced by only 75%. Abolition of tone by the addition of cyanide to the bathing medium did not affect the amplitude of responses to histamine and acetylcholine. The tissue was able to use all the chosen alternative substrates to different degrees for acetylcholine-induced contraction; similarly, with the exception of β-hydroxybutyrate it could use all substrates to some degree to support responses to histamine. The evidence suggests that the source of energy required to maintain tone is different from the source required to sustain K+or agonist-induced contractions, and that the dependence of isotonic contractions on exogenous substrates varies with the pharmacologic stimulus.