Anoxic exposure in the @entity519 -tolerant freshwater turtle is attended by substantial decreases in heart rate and blood flows, but systemic blood pressure (P(sys)) only decreases marginally due to an increase in systemic peripheral resistance (R(sys)). Here, we investigate the role of the alpha-adrenergic system in modulating R(sys) during @entity519 at 5 degrees C and 21 degrees C in the turtle @entity8308 , and also describe how @entity519 affects relative systemic blood flow distribution (%.Q(sys)) and absolute tissue blood flows. Turtles were instrumented with an arterial cannula for measurement of P(sys) and ultrasonic flow probes on major @entity998 ((.Qsys)). Alpha-adrenergic tone was assessed from vascular injections of alpha-adrenergic agonists and antagonists ( @entity2647 and @entity5521 , respectively) during normoxia and following either 6 h (21 degrees C) or 12 days (5 degrees C) of anoxic submergence. Coloured microspheres, injected through a left atrial cannula during normoxia and @entity519 , as well as after alpha-adrenergic stimulation and blockade during @entity519 at both temperatures, were used to determine relative and absolute tissue blood flows. @entity519 was associated with an increased R(sys) and functional alpha-adrenergic vasoactivity at both acclimation temperatures. However, while @entity519 at 21 degrees C was associated with a high systemic alpha-adrenergic tone, the progressive increase of R(sys) at 5 degrees C was not mediated by alpha-adrenergic control. A redistribution of blood flow away from ancillary vascular beds towards more vital circulations occurred with @entity519 at both acclimation temperatures. %.Q(sys) and absolute blood flow were reduced to the digestive and urogenital tissues (approximately 2- to 15-fold), while %.Q(sys) and absolute blood flows to the heart and brain were maintained at normoxic levels. The importance of liver and muscle glycogen stores in fueling anaerobic metabolism were indicated by increases in %.Q(sys) to the muscle at 21 degrees C (1.3-fold) and liver at 5 degrees C (1.7-fold). As well, the crucial importance of the turtle shell as a buffer reserve during anoxic submergence was indicated by 40-50% of .Q(sys) being directed towards the shell during @entity519 at both 5 degrees C and 21 degrees C. Alpha-adrenergic stimulation and blockade during @entity519 caused few changes in %.Q(sys) and absolute tissue blood flow. However, there was evidence of alpha-adrenergic vasoactivity contributing to blood flow regulation to the liver and shell during anoxic submergence at 5 degrees C.

Alpha-adrenergic regulation of systemic peripheral resistance and blood flow distribution in the turtle XXXX during anoxic submergence at 5 degrees C and 21 degrees C.

@entity998 :: ('MESH:D002303', 'Disease') :: ['systemic blood vessels for determination of systemic cardiac output'] @entity5521 :: ('MESH:D010646', 'Chemical') :: ['phentolamine'] @entity8308 :: ('34903', 'Species') :: ['Trachemys scripta'] @entity519 :: ('MESH:D000860', 'Disease') :: ['anoxia', 'Anoxia'] @entity2647 :: ('MESH:D010656', 'Chemical') :: ['phenylephrine']
@entity8308 :: (34903,Species) :: ['Trachemys scripta']
