기니픽(guinea-pig) 기관평활근에 대한 Propofol과 Ketamine의 이완효과

Abstract

BACKGROUND Propofol inhibits postoperative bronchospasm. Ketamine prevents bronchospasm in asthmatic patients. The present study was designed to evaluate the effects and mechanisms of propofol and ketamine on tracheal smooth muscles. METHODS After isolating guinea-pig tracheal preparations, the maximal tracheal tones were induced by smooth muscle constrictors(2 10 7 M carbachol, 10 5 M histamine, 30 mM K+ Krebs solution, 124 mM K+ Krebs solution). When tracheal tones stabilized, propofol or ketamine was added cumulatively to obtain the concentration-relaxation curves, and calculated the ED50 and ED95. RESULTS Propofol and ketamine decreased maximal tracheal tones in the concentration-dependent manners. The ED50 and ED95 of propofol were lowest in the histamine group, highest in the 30 mM K+ Krebs solution group. The ED50 and ED95 of ketamine were lowest in the 124 mM K+ Krebs solution group, highest in the histamine group. CONCLUSIONS The relaxant effects of propofol and ketamine involve with all receptors in nonspecific way. However, propofol may inhibit more strongly the histamine mediated mechanism of tracheal contraction and ketamine may involve more strongly with Ca++ channel.