The Journal of physiology
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The Journal of physiology · Sep 1982
Comparative StudyReflex response of the rabbit hind-limb muscle vascular bed to baroreceptor stimulation and its modification by pregnancy.
1. The pressure--flow relationship of the blood-perfused skinned hind limb has been compared in primigravid pregnant and virgin non-pregnant rabbits while pressure within the vascularly isolated carotid sinus was held at a series of non-pulsatile values. 2. At each level of sinus pressure the slope of the pressure--flow relationship was steeper in the pregnant animals. ⋯ There seemed to be a small reduction in the range and gain of the reflex in the pregnant group but this was not statistically significant. 5. We have previously shown total peripheral resistance in the pregnant rabbit to be less than that in the non-pregnant rabbit at the same level of sinus pressure. The lower hind-limb vascular resistance of the pregnant rabbit at any given sinus pressure must contribute to this reduced total peripheral resistance.
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The Journal of physiology · Sep 1982
Comparative StudyThe response of the hind-limb vascular bed of the rabbit to sympathetic stimulation and its modification by pregnancy.
1. Pressure-flow relationships in the hind limb, perfused with blood at a series of constant flows, have been compared in primigravid and virgin rabbits following section of the lumbar sympathetic chain. 2. In the absence of sympathetic stimulation perfusion pressure was lower (P less than 0.05) in the pregnant rabbits at all levels of flow to the leg. 3. ⋯ Examination of the pressure-flow curves suggests that when, as in these experiments, flow is held constant, the ability of sympathetic stimulation to increase the resistance to blood flow is reduced in pregnancy. However, if these pressure-flow curves are used to predict the change of flow that would occur at a constant perfusion pressure, the response to sympathetic stimulation appears to be greater in pregnancy. 7. Further analysis of the findings, based on certain assumptions, suggests that differences between the pressure-flow curves of pregnant and non-pregnant animals during sympathetic stimulation are due in the main to either a differing size of the unstimulated vascular beds or a differing compliance of their vessel walls, rather than to any intrinsic alteration in their response to sympathetic stimulation.