Effect of aminophylline on hindlimb blood flow autoregulation during increased metabolism in dogs.
The contribution of adenosine to hindlimb blood flow autoregulation during treadmill exercise or the administration of 2,4-dinitrophenol (DNP) was evaluated in 9 conscious dogs by determining hindlimb vascular bed pressure-flow relationships in the presence and absence of the adenosine receptor site antagonist, aminophylline. Hindlimb pressure-flow relationships were obtained by measuring blood flow during stepwise reductions in perfusion pressure produced with an occlusion cuff located distal to a flow probe on the external iliac artery. The efficiency of autoregulation was quantitated by calculating the closed-loop gain of flow regulation (Gc) at each pressure decrement utilizing the equation Gc = 1 - (% delta flow/% delta pressure). A Gc of one represents perfect autoregulation of flow, and a Gc of zero is indicative of a rigid system. During exercise, Gc averaged 0.44 +/- 0.07. Aminophylline reduced the Gc during exercise to -0.07 +/- 0.06 (P less than 0.05). During DNP administration, Gc averaged 0.54 +/- 0.09 and declined to -0.09 +/- 0.10 in the presence of aminophylline (P less than 0.05). These results support the hypothesis that adenosine is a primary mediator of hindlimb blood flow autoregulation during conditions that increase hindlimb metabolism.
D019297:2,4-Dinitrophenol; D000241:Adenosine / Q000494:pharmacology; D000628:Aminophylline / Q000494:pharmacology*; D000818:Animals; D004140:Dinitrophenols / Q000494:pharmacology; D004285:Dogs; D005260:Female; D006614:Hindlimb / Q000098:blood supply* / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects*; D010477:Perfusion; D005082:Physical Exertion; D011312:Pressure; D012039:Regional Blood Flow / Q000187:drug effects
D004140:Dinitrophenols; D000628:Aminophylline; D000241:Adenosine; D019297:2,4-Dinitrophenol