三种拟胆碱药对兔中枢作用的比较

给兔icv毛果芸香碱,出现抽搐、流涎、咀嚼,脑电呈低幅快波,呼吸兴奋,icv槟榔碱,兔轻度抽搐、流涎,脑电呈双相反应,呼吸兴奋作用短暂;icv氨甲酰甲胆碱,兔亦出现抽搐、流涎、咀嚼及脑电低幅快波反应,但呼吸变化不一,或为加快,或为减慢。提示三种拟胆碱药中枢作用不完全相同,其原因可能与选择性激动中枢不同亚型M受体有关。上述三药均引起心率减慢。

COMPARATIVE STUDY ON CENTRAL EFFECTS OP SOME CHOLINOMIMETICS

Pilocarpine 0.6-2.5 mg/kg icv to rabbits produced restlessness, frequcnt twitching in limbs, profuse salivation, chewing movement and low voitage rapid wave ( LV-RW ), with epileptoid firing observed in one animal. Their respiration rate was increased by 63-141% in a linear dose~eifecl fashion (P<0.05-0.01 ) , with ventilation of lungs increased. Arecoline 0.1-0.4 mg/kg icv to rabbits produced mild twitching, salivation, biphasci reaction in EEG ( initial LV-RW followed by high voltage slow wave, ( HV-RW ) 30 min afterwads ) .Their respiration was increased by 112-162% ( P<0.05 -0.01 ) , which was dose-effect dependent but lasted for only 20min. Bethanechol 1.0 mg/kg icv to rabbits elicited frequent twitching and salivation. EEC showed LV-RW, with epileptoid firing in 3/5 of the animals. Their respiratory response was varying, some accelerated and some slowed. Combined use of atropine ( 0.05 mg/kg icv ) with any of the 3 drugs caused epileptoid firing in EEG, while the addition of scopolamine (5.0 mg/ kg icv ) resulted in HV-RW invariably. 4-Aminopykidine ( 1.0 ug/kg icv ) accelerated the respiratory rate by 48% ( P<0.01 ) , which, however, might be abolished by administering hemieholine beforehand. These results suggest : ( 1 ) There are some differences in the central effects of the 3 cholinomimetics. Perhaps pilocarpine selectively acts on the exitatory M1 receptor while arecoline and bethanechol on both M1 and M2 receptors. ( 2 ) The central cholinergic mechanism is involved in the modulation of respiratory center.