RESUMO
The effect of bombesin on the tone and the responses of strips from the lower esophageal sphincter (LES) to field electrical stimulation (FES) (2 Hz, 0.2 ms, supramaximal current intensity, 20 s duration) was studied. Bombesin dose-dependently increased the LES tone. The threshold for this effect was 10(-14) M and was particularly pronounced with a concentration of 10(-8) M. The response reached maximum between the 3rd and the 5th min after application, persisted for 15-20 min, and was followed by a slight time-dependent decrease. Bombesin increased FES-produced relaxation of LES by 39% as compared to the control. The potentiating effect of bombesin on the LES relaxation was also observed after cholinergic and adrenergic receptor blockade. It is concluded that bombesin may modulate the release of cholinergic, adrenergic and noncholinergic, nonadrenergic inhibitory neurotransmitters.
Assuntos
Bombesina/farmacologia , Junção Esofagogástrica/efeitos dos fármacos , Tono Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Animais , Atropina/farmacologia , Gatos , Estimulação Elétrica , Junção Esofagogástrica/fisiologia , Relaxamento Muscular/efeitos dos fármacos , Músculo Liso/fisiologia , Fentolamina/farmacologia , Propranolol/farmacologia , Tetrodotoxina/farmacologiaRESUMO
The electrical activity of the stomach and duodenum of six mongrel dogs was studied under chronic conditions after partial resection of the pancreas and occlusion of the pancreatic duct. Changes in the electrical activity were observed only in the stomach, manifested in the form of groups of slow potentials with accelerated rhythm (over 7 cpm--tachygastria) or delayed rhythm (below 3 cpm--bradygastria). A definite dynamics was observed in the appearance and development of rhythmic disorganization. The duration of the groups of slow potentials with abnormal rhythm increased 10-12 days after surgery. Radioimmunological studies showed a postoperative increase in the glucagon level, paralleled by a decrease in the content of the C-peptide and insulin in the blood plasma. Influsion with insulin (0.5 IU i.v.) regulates the disorganized antral rhythm. The dysbalance in the insulin/glucagon ratio in the blood serum is assumed to be the probable mechanism of the rhythmic disturbances.
