Effect of selective [beta]-adrenoceptor blockade and surgical resection of the celiac-superior mesenteric ganglion complex on delayed liquid gastric emptying induced by dipyrone, 4-aminoantipyrine, and antipyrine in rats

There is evidence for participation of peripheral [beta]-adrenoceptors in delayed liquid gastric emptying (GE) induced in rats by dipyrone (Dp), 4-aminoantipyrine (AA), and antipyrine (At). The present study aimed to determine whether [beta]-adrenoceptors are involved in delayed GE induced by phenylpyrazole derivatives and the role of the prevertebral sympathetic nervous system in this condition. Male Wistar rats weighing 220-280 g were used in the study. In the first experiment rats were intravenously pretreated with vehicle (V), atenolol 30 mg/kg (ATE, [[beta].sub.1]-adrenergic antagonist), or butoxamine 25 mg/kg (BUT, [[beta].sub.1]-adrenergic antagonist). In the second experiment, rats were pretreated with V or SR59230A 2 mg/kg (SRA, [[beta].sub.1]-adrenergic antagonist). In the third experiment, rats were subjected to surgical resection of the celiac-superior mesenteric ganglion complex or to sham surgery. The groups were intravenously treated with saline (S), 240 [micro]mol/kg Dp, AA, or At, 15 min after pretreatment with the antagonists or V and nine days after surgery. GE was determined 10 min later by measuring the percentage of gastric retention (%GR) of saline labeled with phenol red 10 min after gavage. The %GR (means [+ or -] SE, n=6) values indicated that BUTabolished the effect of Dp (BUT + Dp vs V + Dp: 35.0% [+ or -] 5.1% vs 56.4% [+ or -] 2.7%) and At (BUT + At vs V + At: 33.5% [+ or -] 4.7% vs 52.9% [+ or -]2.6%) on GE, and significantly reduced (P