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Effect of tetrandrine on morphine dependence in isolated guinea pig ileum
Aim:
To evaluate the effects of tetrandrine (Tet) and nimodipine (Nim) on the morphine (Mor) withdrawal response in the isolated guinea pig ileum.
Methods:
The withdrawal contracture was elicited by addition of naloxone (Nal) (1 mumol.L-1) to the isolated naive ileum incubated with Mor (3 mumol.L-1) at 37.5 degrees C for 4 h or to the ileum obtained from Mor-dependent guinea pig.
Results:
When Nim (0.01, 0.05, and 0.1 mumol.L-1) or Tet (1, 10, and 50 mumol.L-1) was added 1 min before Nal in the naive ilea bathed in Krebs solution containing Mor, or when the ilea from Mor-dependent guinea pigs were incubated with Nim (0.01, 0.05, and 0.1 mumol.L-1) or Tet (1, 10, and 50 mumol.L-1) for 15 min, or when Nim (5 and 10 mg.kg-1, i.p.) or Tet (15 and 30 mg.kg-1, i.p.) was administered in vivo to Mor-dependent guinea pigs, the Nal-precipitated withdrawal contracture was significantly decreased in a dose-dependent manner.
Conclusion:
Tet and Nim, Ca2+ channel blockers, could inhibit the Nal-precipitated Mor withdrawal response in the isolated guinea pig ileum.