Involvement of imidazoline and opioid receptors in the enhancement of clonidine-induced analgesia by sulfisoxazole.

Clonidine, an alpha2-adrenergic agonist, has been demonstrated to produce significant analgesia and potentiate morphine analgesia. Endothelin (ETA) receptor antagonists have also been found to potentiate the antinociceptive response to morphine. Clonidine and ET have been reported to have cardiovascular interactions involving the sympathetic nervous system, but it is not known whether ETA receptor antagonist affects clonidine analgesia.

Determination of adrenergic and imidazoline receptor involvement in augmentation of morphine and oxycodone analgesia by clonidine and BMS182874.

Background: Numerous agents have been demonstrated to potentiate morphine analgesia, including clonidine (alpha(2)-adrenergic and I(1)-imidazoline receptor agonist) and BMS182874 (endothelin-A, ET(A,) receptor antagonist). ET has been shown to affect pharmacological actions of clonidine. The present study was conducted to determine whether alpha(2)-adrenergic and/or I(1)-imidazoline receptors are involved in the augmentation of morphine and oxycodone analgesia by clonidine and BMS182874.

IRL-1620, a tumor selective vasodilator, augments the uptake and efficacy of chemotherapeutic agents in prostate tumor rats.

Background: IRL-1620, a potent endothelin B receptor agonist, enhanced the efficacy of paclitaxel in a breast tumor model, but its effect in prostate cancer is not known. The present study was conducted to evaluate the effect of IRL-1620 on tumor perfusion, uptake of [(14)C]-doxorubicin in the tumor and efficacy of doxorubicin (DOX), and 5-flurouracil (5-FU) in a rat prostate tumor model.

Methods: JHU-4 (Mat-Lu) cells inoculated prostate tumor model in Copenhagen rats was used for the study.

Endothelin ETA receptor blockade potentiates morphine analgesia but does not affect gastrointestinal transit in mice.

Development of analgesic tolerance and constipation remain a major clinical concern during long-term administration of morphine in pain management. Central endothelin mechanisms are involved in morphine analgesia and tolerance. The present study was conducted to investigate the effect of intracerebroventricular (i.

Involvement of central endothelin receptors in neonatal morphine withdrawal.

The involvement of central endothelin (ET) receptors in neonatal morphine tolerance has been demonstrated. The present study investigates the role of central ET receptors in morphine withdrawal in neonatal rats. The aim was to determine whether activation of G-proteins coupled to opioid and ET receptors by morphine and various ET receptor modulators is affected during morphine withdrawal in neonatal rats.