Cardiovascular and Metabolic Responses to Carotid Clamping in Anemic Dogs
It has been observed that blood flow to the hindlimb was maintained or even increased in proportion to cardiac output during isovolemic hemodilution of anesthetized dogs with dextran (Grupp et al., 1972; Cain and Chapler, 1978; 1981). This was true even when the decrease in total O2 transport limited whole body O2 uptake. In one study, we infused norepinephrine to increase vasoconstrictor tone. The results suggested that the reduction in viscosity prevented any measurable increase in hindlimb resistance during anemia so that blood flow could not be redistributed to areas more essential than resting skeletal muscle. In these new experiments we have used a more physiologic cardiovascular challenge, clamping of the carotid arteries, to see if lowered blood viscosity alters the response to baroreceptor stimulation. As will be shown, the buffering effect of aortic baroreceptors prevented much change in the peripheral resistance but carotid clamping did alter O2 uptake.
KeywordsCardiac Output Stroke Volume Stroke Work Systemic Arterial Blood Pressure Limb Blood Flow
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