Kiel J W, Bishop V S
Department of Pharmacology, University of Texas Health Science Center, San Antonio 78284.
Am J Physiol. 1992 May;262(5 Pt 2):H1407-14. doi: 10.1152/ajpheart.1992.262.5.H1407.
To determine whether feeding improves the efficacy of mesenteric autoregulation in conscious animals, rabbits were instrumented with pulsed-Doppler flow probes on the superior mesenteric artery and distal abdominal aorta to record mesenteric and hindquarters blood flow velocity. Hydraulic occluders were placed on the abdominal aorta (just below the celiac artery) and the thoracic vena cava to vary mesenteric and hindquarters arterial pressure (MAP), which was monitored via a catheter positioned in the distal abdominal aorta. Heart rate (HR) and lumbar sympathetic nerve activity (LSNA) were monitored as indexes of sympathetic nervous system activity. Pressure-velocity curves were obtained by aortic and caval occlusions on two consecutive days; first after a 24-h fast and after approximately 24 h of ad libitum refeeding. In the fed state, mesenteric velocity was significantly increased and MAP was decreased slightly; the slight decrease in MAP was counteracted by significant increases in HR and LSNA, whereas hindquarters perfusion was unchanged. The mesenteric and hindquarters pressure-velocity curves were all highly linear (r greater than or equal to 0.9) and showed no evidence of autoregulation in the fasted or fed state when pressure was changed by either the aortic or the caval occlusions. We conclude that autoregulation plays a minor role in the short-term regulation of mesenteric blood flow in the conscious rabbit.
为了确定进食是否能提高清醒动物肠系膜自动调节的功效，给家兔在肠系膜上动脉和腹主动脉远端安装了脉冲多普勒血流探头，以记录肠系膜和后肢的血流速度。在腹主动脉（腹腔动脉下方）和胸段腔静脉放置液压阻断器，以改变肠系膜和后肢的动脉血压（MAP），通过置于腹主动脉远端的导管监测该血压。监测心率（HR）和腰交感神经活动（LSNA）作为交感神经系统活动的指标。在连续两天通过主动脉和腔静脉阻断获取压力-速度曲线；第一天是在禁食24小时后，第二天是在自由进食约24小时后。在进食状态下，肠系膜血流速度显著增加，MAP略有下降；MAP的轻微下降被HR和LSNA的显著增加所抵消，而后肢灌注没有变化。当通过主动脉或腔静脉阻断改变压力时，肠系膜和后肢的压力-速度曲线均呈高度线性（r大于或等于0.9），并且在禁食或进食状态下均未显示出自动调节的迹象。我们得出结论，自动调节在清醒家兔肠系膜血流的短期调节中起次要作用。
