RESUMEN
The motility of the gallbladder (GB) consists of collection, storage and delivery of bile. GB motor functions are controlled by its extrinsic and intrinsic innervation, and humoral factor. In the fasting stage, GB motility is associated with phase 3 of the interdigestive migrating myoelectric complex and increased plasma motilin concentrations. In the fed state cholecystokinin (CCK) is the primary mediator of GB contraction. Extrinsic neural control of GB motility appears to play a role in the mediation of cephalic phase of GB emptying. Vagal stimulation induces GB concentration, and sympathetic stimulation induces GB relaxation via cholinergic, adrenergic, and noncholinergic, nonadrenergic neurotransmitters. Intrinsic neural control of GB motility is mediated by such neuropeptides as pancreatic polypeptide, somatostatin, bombesin, neuropeptide Y, calcitonin gene-related peptide, vasoactive intestinal polypeptide, CCk, tachykinins and nitric oxide.
Asunto(s)
Vaciamiento Vesicular/fisiología , Neurotransmisores/fisiología , Ingestión de Alimentos/fisiología , Ayuno/fisiología , Humanos , Valores de ReferenciaRESUMEN
This study was designed to evaluate the role of adenosine and adenosine receptors in the reactive (RH) and functional hyperemia (FH) in rat gut. Experiments were performed on anesthetized rats. Mesenteric blood flow was measured with a pulsed Doppler flowmeter. We also determined the duration of reactive hyperemia, excess volume of blood flow above control value and maximal increase in mesenteric vascular conductance during both hyperemic responses. Data were collected following release from occlusions lasting 30, 60 and 120 sec. Functional hyperemia was induced by perfusion of the gut with a solution. Studied parameters were obtain before and after adenosine deaminase (ADA) and two adenosine receptor antagonists: 8-phenyltheophylline (8-PT) and 1.3-dipropyl-7-methyl-xanthine (DPMX). In fasted rats ADA and 8-PT reduced of RH after each period of occlusion and DPMX was ineffective in reducing any parameter of RH. In fed rats control mesenteric blood flow was increased. ADA, 8-PT, and DPMX were more effective inhibitors of RH and FH. Above findings suggest that adenosine play a role in the modulation of RH and FH acting on A2 subtype receptors.