E.Y. Trofimova, V.M. Smirnov, D.S. Sveshnikov, A.V. Kuchuk

Experiments were performed in 61 Wistar rats anesthetized by nembual (60mg/kg) in 5 series. 273 motor responses of the bowel to intraarterial serotonin infusion (0.05, 0.1, 0.15 mg/kg) of the bowel were recorded in intact animals and during simultaneous blockade of adreno- and cholinoreceptors (in last case dosage of serotonin was 0.1 mg/kg). It was shown, that optimal serotonin dosage that provide pronounced motor effect of the colon was 0.1 mg/kg. The study of different 5-HT receptor subtype was performed during simultaneous blockade of α- and β- adrenoreceptors and M- and N- ACh-receptors for data confirmation. 5-HT1b- receptors blockade by NAS-181 and 5-HT3-blockade by MDL 72222 demonstrate the presence of current receptors in autonomous ganglia because positive motor responses to serotonin did not eliminate by using the blocker. 5-HT2- receptors blockade by SB 204741 and 5-HT4- receptors by RS 39604 blockade by neutralized reactions to serotonin so this is an evidence of 5-HT2, 5-HT4 locations in smooth muscles. These findings also confirmed the presence of serotoninergic structures that stimulate GI motility.