Enhancement by levamisole of the contractions induced by prostaglandin E2 in the guinea-pig isolated ileum

The effect of levamisole on sheep trachea alone and with trichlorfon combination

The aim of this study is to determine the effect of levamisole and levamisole-trichlorfon combination on isolated sheep trachea. Contraction was achieved with levamisole concentrations (10(-8)-10(-3) M) on tracheal strips of adult sheep (> 1 year of age). Pretreatment with trichlorfon (10(-7) M)-levamisole (10(-7) M) decreased the pD2 and E(max) of Ach when compared to levamisole pretreatment (p < or = 0.01). Pretreatment with levamisole (10(-7) M), decreased the E(max) (p < or = 0.01) and pD2 (p < 0.05) of bethanechol concentrations (10(-8)-10(-3) M) significantly. Pretreatment with atropine (10(-6) M) decreased the E(max) of levamisole (10(-4) M) significantly (p < 0.05). To conclude, levamisole acted mainly on the muscarinic receptors of the sheep trachea and this effect was partly inhibited by atropine. Adverse interaction was present between levamisole and trichlorfon.

Levamisole inhibits in vivo rat platelet aggregation by a release of prostacyclin-like factor

1. The anti-thrombotic effect of levamisole (LMS) and acetylsalicylic acid (ASA) were examined in vitro and in vivo models. 2. LMS inhibits rat platelet aggregation induced by either adenosine 5'-diphosphate (ADP) or collagen (CLG) in vitro and in vivo. 3. LMS is more active in vivo than in vitro while acetylsalicylic acid (ASA) is more active in vitro than in vivo. It seems that in vivo LMS does not act by blocking thromboxane A2 formation only, but via participation of an endogenous factor. 4. The release of LMS-induced anti-thrombotic factor is inhibited by ASA pretreatment, indicating to be a cyclooxygenase metabolite of arachidonic acid. 5. The LMS-induced anti-thrombotic factor has a t1/2 of 3.6 +/- 0.8 min that is similar to the t1/2 of synthetic prostacyclin (PGI2) tested in our system (3.9 +/- 0.5 min; P = NS). 6. The release of PGI2-like substance from vascular tissue is LMS dose-dependent.