Jones D R, Milsom W K, Gabbott G R
Am J Physiol. 1982 Nov;243(5):R537-45. doi: 10.1152/ajpregu.1982.243.5.R537.
Using techniques of vascular isolation and subsequent perfusion we have investigated the effects of altering blood gas tensions, in the cerebral and carotid body circulations, on some cardiovascular responses to diving in unanesthetized ducks. After denervating the right carotid body, perfusion of the innervated left carotid body with hyperoxic blood significantly reduced diving bradycardia and reduced the increase in hindlimb vascular resistance (HLVR) in 1-min dives compared with dives in which the innervated carotid body was autoperfused. Denervation of systemic arterial baroreceptors reduced the fall in heart rate (HR) and increased the rise in HLVR in all dives. Cross-perfusion of the head, from a donor with blood of normal blood gas tensions, did not significantly affect HR or HLVR in 2-min dives compared with dives in which the head was autoperfused. however, cross-perfusing the cerebral circulation with blood of elevated PaCO2 caused significantly greater increases in HLVR than when high PaCO2 only affected the peripheral circulation. We conclude that peripheral chemoreceptors cause virtually all the bradycardia in the later stages of a dive but only about one-half the increase in HLVR, a significant contribution comes from the stimulation of central chemoreceptors with blood of high PaCO2.
我们运用血管分离及随后灌注的技术，研究了在未麻醉鸭的脑循环和颈动脉体循环中，改变血气张力对潜水时某些心血管反应的影响。在切除右侧颈动脉体的神经后，与对支配的颈动脉体进行自身灌注的潜水相比，用高氧血灌注支配的左侧颈动脉体可显著降低潜水时的心动过缓，并减少1分钟潜水时后肢血管阻力（HLVR）的增加。去神经支配全身动脉压力感受器可降低所有潜水中心率（HR）的下降，并增加HLVR的上升。与头部自身灌注的潜水相比，用血气张力正常的供血者的血液对头部进行交叉灌注，在2分钟潜水中对HR或HLVR没有显著影响。然而，用PaCO2升高的血液对脑循环进行交叉灌注，与高PaCO2仅影响外周循环时相比，会导致HLVR显著更大程度的增加。我们得出结论，外周化学感受器几乎导致了潜水后期所有的心动过缓，但仅导致HLVR增加的约一半，高PaCO2血液对中枢化学感受器的刺激也起到了重要作用。
