Kao S J, Shen C Y, Wang D, Chen H I
Department of Medicine, Tri-Service General Hospital, Taipei, Taiwan, Republic of China.
Chin J Physiol. 1989;32(1):21-30.
In anesthetized dogs, we studied the effects of colonidine on the changes in pulmonary collateral resistance in response to histamine challenge. In the whole lung, an intravenous histamine increased the inspiratory (Ri), and expiratory (Re) resistance by 142 +/- 12%, and 229 +/- 30% over the control, respectively. Pretreatment with clonidine (0.05 mg/kg, iv) significantly attenuated the increases to 76 +/- 16% (Ri), and 114 +/- 22% (Re) (p less than 0.05). However, the responses to histamine were restored after an addition of yohimbine (0.15 mg/kg, iv) before clonidine. A bronchoscope wedge technique was used to measure the collateral resistance (Rcs) in the lung periphery. Histamine was administered in aerosolized form to a wedged sublobar segment. The local histamine challenge significantly increased Rcs. Pretreatment with clonidine did not discernibly affect the histamine-induced increase in Rcs. On the other hand, pretreatment with isoproterenol (0.02 mg/kg, iv) remarkably attenuated the Rcs response to histamine. The results indicate that alpha 2-adrenergic agonism with clonidine inhibits the bronchoconstriction induced by histamine. alpha 2- antagonism with yohimbine abolishes the antiasthmatic effect of clonidine. In the lung periphery, the Rcs response to histamine is not altered by alpha 2, but by beta 2 adrenergic agonism with isoproterenol.
在麻醉犬中，我们研究了可乐定对组胺激发试验引起的肺侧支阻力变化的影响。在全肺中，静脉注射组胺使吸气阻力（Ri）和呼气阻力（Re）分别比对照增加142±12%和229±30%。可乐定（0.05mg/kg，静脉注射）预处理可使增加幅度显著减弱至76±16%（Ri）和114±22%（Re）（p<0.05）。然而，在可乐定给药前加入育亨宾（0.15mg/kg，静脉注射）后，对组胺的反应恢复。采用支气管镜楔压技术测量肺周边的侧支阻力（Rcs）。将组胺雾化后给予楔压的肺段小叶。局部组胺激发试验显著增加了Rcs。可乐定预处理对组胺诱导的Rcs增加无明显影响。另一方面，异丙肾上腺素（0.02mg/kg，静脉注射）预处理显著减弱了Rcs对组胺的反应。结果表明，可乐定的α2-肾上腺素能激动作用抑制了组胺诱导的支气管收缩。育亨宾的α2-拮抗作用消除了可乐定的抗哮喘作用。在肺周边，Rcs对组胺的反应不受α2的影响，而是受异丙肾上腺素的β2-肾上腺素能激动作用的影响。
