儿茶酚胺和组胺对豚鼠输尿管平滑肌兴奋作用的机制。

The mechanism of the excitatory action of catecholamines and histamine on the smooth muscle of guinea-pig ureter.

作者信息

Shuba M F

出版信息

J Physiol. 1977 Jan;264(3):853-64. doi: 10.1113/jphysiol.1977.sp011698.

DOI:10.1113/jphysiol.1977.sp011698

PMID:845827

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1307795/

Abstract

The ionic mechanism of the excitatory action of catecholamines and histamine on the smooth muscle cells of guinea-pig ureter was studied with the double sucrose-gap method. 2. In normal conditions adrenaline and noradrenaline in a concentration of 10(-5) g/ml., and histamine in a concentration of 10(-6) g/ml., prolonged the duration of the plateau of the action potential and increased the amplitude and duration of the phasic contraction. Sometimes these changes were accompanied by a slight depolarization of the muscle membrane and by a small increase (with noradrenaline) or decrease (with histamine) of the membrane resistance. The amplitude and duration of the fast spike component of the action potential were not changed. 3. Isoprenaline in a concentration of 10(-5) g/ml. either caused no change or it decreased the duration of the plateau, reduced the amplitude of contractions and reduced excitability. 4. Tetraethyl ammonium (TEA; 5 mM), which blocks the delayed outward K current, did not prevent the increase in the duration of the plateau nor the increase of the amplitude and duration of the contractions by noradrenaline and histamine. 5. In Na-free or in K-free solution or in the presence of ouabain, i.e. in conditions in which the Na-gradient across the membrane was reduced, noradrenaline and histamine were unable to increase the duration of the plateau and the amplitude and duration of the contraction. 6. In the presence of Mn2+ (2 mM) which suppressed the spike component of tha action potential and the phasic contraction, theeffects of noradrenaline and histamine were almost abolished. 7. The results suggest a dual ionic mechanism of the alpha-action of catecholamines and of the action of histamine on the smooth muscle of ureter: (1) these drugs affect the passive ionic permeability of the membrane in a manner that results in depolarization; (2) they specifically activate the potential-dependent conductance of the slow Na channels, thereby increasing the plateau duration. The increased amplitude and duration of the contraction is the result of their primary effect on the plateau of the action potential.

摘要

采用双蔗糖间隙法研究了儿茶酚胺和组胺对豚鼠输尿管平滑肌细胞兴奋作用的离子机制。2. 在正常情况下，浓度为10(-5) g/ml的肾上腺素和去甲肾上腺素，以及浓度为10(-6) g/ml的组胺，可延长动作电位平台期的持续时间，并增加相性收缩的幅度和持续时间。有时这些变化伴随着肌膜的轻微去极化以及膜电阻的小幅增加（去甲肾上腺素）或降低（组胺）。动作电位快速尖峰成分的幅度和持续时间未改变。3. 浓度为10(-5) g/ml的异丙肾上腺素要么无变化，要么缩短平台期持续时间，降低收缩幅度并降低兴奋性。4. 阻断延迟外向钾电流的四乙铵（TEA；5 mM）并不能阻止去甲肾上腺素和组胺使平台期持续时间增加以及收缩幅度和持续时间增加。5. 在无钠或无钾溶液中或存在哇巴因的情况下，即在跨膜钠梯度降低的条件下，去甲肾上腺素和组胺无法增加平台期持续时间以及收缩幅度和持续时间。6. 在存在抑制动作电位尖峰成分和相性收缩的Mn2+（2 mM）时，去甲肾上腺素和组胺的作用几乎被消除。7. 结果提示儿茶酚胺的α作用和组胺对输尿管平滑肌作用的双重离子机制：(1) 这些药物以导致去极化的方式影响膜的被动离子通透性；(2) 它们特异性激活慢钠通道的电压依赖性电导，从而增加平台期持续时间。收缩幅度和持续时间的增加是它们对动作电位平台期的主要作用的结果。