Clerici C, Harf A, Macquin-Mavier I
Br J Pharmacol. 1987 Jul;91(3):487-92. doi: 10.1111/j.1476-5381.1987.tb11241.x.
The effect of labetalol on histamine-induced bronchoconstriction was studied in anaesthetized guinea-pigs. Unlike propranolol (1 mg kg-1), the same dose of labetalol did not enhance histamine-induced bronchoconstriction. To determine whether the absence of enhancement of the respiratory effects of histamine by labetalol was due to its alpha 1-blocking properties or to its partial agonist activity at beta 2-adrenoceptors, the effects of propranolol plus prazosin and of propranolol plus labetalol on histamine-induced bronchoconstriction were examined. In both cases, the bronchoconstrictor effects of histamine were enhanced to the same extent as with propranolol alone. These data support the hypothesis that the non impairment of respiratory mechanics by labetalol is not due to antagonism at alpha-adrenoceptors and may be mediated by its partial agonist activity at beta 2-adrenoceptors.
在麻醉的豚鼠中研究了拉贝洛尔对组胺诱导的支气管收缩的作用。与普萘洛尔（1mg/kg）不同，相同剂量的拉贝洛尔不会增强组胺诱导的支气管收缩。为了确定拉贝洛尔不增强组胺呼吸效应是由于其α1阻断特性还是由于其对β2肾上腺素受体的部分激动剂活性，研究了普萘洛尔加哌唑嗪以及普萘洛尔加拉贝洛尔对组胺诱导的支气管收缩的影响。在这两种情况下，组胺的支气管收缩作用增强的程度与单独使用普萘洛尔时相同。这些数据支持这样的假设，即拉贝洛尔对呼吸力学无损害不是由于对α肾上腺素受体的拮抗作用，可能是由其对β2肾上腺素受体的部分激动剂活性介导的。
