Humphreys P W, Joels N
Department of Physiology, Queen Mary and Westfield College, London, United Kingdom.
Am J Physiol. 1994 Sep;267(3 Pt 2):R780-5. doi: 10.1152/ajpregu.1994.267.3.R780.
Mean circulatory filling pressure (MCFP) has been measured after vagally induced cardiac arrest in 11 nonpregnant and 10 near-term pregnant rabbits, anesthetized with pentobarbital sodium. MCFP was 6.1 +/- 0.4 (SD) mmHg in the nonpregnant and 7.2 +/- 0.4 mmHg in the pregnant animals. The difference of 1.1 mmHg was significant (P < 0.001). Sympathetic blockade with bretylium tosylate (10 mg/kg) reduced MCFP by 0.4 mmHg in both nonpregnant and pregnant rabbits. Vascular capacitance was examined in the two groups. Unstressed vascular volume and vascular compliance were derived from measurements of MCFP after increasing blood volume by 8 and 16% or reducing it by 8%. The unstressed vascular volumes, 33.9 +/- 3.9 (SD) ml/kg in the nonpregnant and 35.1 +/- 3.2 ml/kg in the pregnant group, were not significantly different, but compliance in the pregnant group (4.0 +/- 0.6 ml.kg-1.mmHg-1) was significantly greater than in the nonpregnant rabbits (3.4 +/- 0.6 ml.kg-1.mmHg-1) (P < 0.05). We conclude that there are changes in vascular capacitance in rabbit pregnancy, probably not related to alterations in vasomotor activity, but these are insufficient to fully compensate for the increase in blood volume, thus leading to the rise in MCFP.
用戊巴比妥钠麻醉11只未孕和10只近足月孕兔，在迷走神经诱导心脏骤停后测量其平均循环充盈压（MCFP）。未孕兔的MCFP为6.1±0.4（标准差）mmHg，孕兔为7.2±0.4 mmHg。两者相差1.1 mmHg，具有显著性（P<0.001）。用溴苄铵（10 mg/kg）进行交感神经阻滞，未孕和孕兔的MCFP均降低0.4 mmHg。对两组动物的血管容量进行了检测。通过增加8%和16%的血容量或减少8%的血容量后测量MCFP，得出无应激血管容量和血管顺应性。未孕组的无应激血管容量为33.9±3.9（标准差）ml/kg，孕组为35.1±3.2 ml/kg，两者无显著差异，但孕组的顺应性（4.0±0.6 ml·kg-1·mmHg-1）显著高于未孕兔（3.4±0.6 ml·kg-1·mmHg-1）（P<0.05）。我们得出结论，兔妊娠期间血管容量存在变化，可能与血管运动活性改变无关，但这些变化不足以完全代偿血容量的增加，从而导致MCFP升高。
