EFFECT OF ADRENERGIC AND NITRERGIC BLOCKADE ON EXPERIMENTAL ILEUS IN RATS

1 In a rat model of experimental ileus, the effect of blockade of adre nergic and nitrergic neurotransmission was studied on the intestinal t ransit of Evans blue. 2 Ether anaesthesia and skin incision had no inf luence on the transit. Laparotomy significantly inhibited the transit of Evans blue. This inhibition was even more pronounced when the small intestine was manipulated. 3 Reserpine (5 mg kg(-1)), a drug that blo cks adrenergic neurotransmission, completely reversed the inhibition o f the transit induced by laparotomy but only partially reversed that i nduced by laparotomy with manipulation of the small intestine. 4 N-ome ga-nitro-L-arginine (L-NOARG, 5 mg kg(-1)), a nitric oxide synthase in hibitor, completely reversed the reserpine-resistant inhibition induce d by laparotomy with manipulation of the small intestine. The effect o f L-NOARG was prevented by concomitant administration of L-arginine, L -Arginine itself slightly, but significantly enhanced the inhibition. S-methylisothiourea and aminoguanidine, selective inhibitors of the in ducible NO synthase, had no effect on the transit after the three oper ations. 5 Treatment of the rats with reserpine plus L-NOARG had no add itional effect on the transit after Laparotomy as compared to reserpin e alone. However, reserpine plus L-NNA completely reversed the inhibit ion of the transit induced by laparotomy with manipulation of the smal l intestine. 6 These findings support the involvement of adrenergic pa thways in the pathogenesis of ileus and suggest that the additional in hibitory effect of mechanical stimulation results from an enhanced rel ease of NO by the constitutive NO synthase.