[Role of adenosine in functional and reactive intestinal hyperemia]

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.