Abstract
1. 1. The repetitive application of morphine gradually induced a contracture in the isolated guinea pig ileum. 2. 2. The optimum conditions for induction of the contracture were as follows: the concentration, incubation time and washout time of morphine were 1 or 10 μM, 2 and 3 min, respectively. 3. 3. Preincubation with naloxone or TTX blocked this morphine-induced contracture. 4. 4. Among twitch-inhibiting drugs, only clonidine induced a contracture similar to that induced by morphine, while tetrodotoxin (TTX) and adenosine did not. 5. 5. The contracture was also observed in the longitudinal muscle-myenteric plexus preparations. 6. 6. These findings indicate that morphine has a dual inhibitory and excitatory action on the guinea pig ileum and that its repetitive application preferentially diminish the inhibitory one.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
