Humphreys P W, Joels N
J Physiol. 1985 Sep;366:17-25. doi: 10.1113/jphysiol.1985.sp015782.
The changes in arterial blood pressure and cardiac output following rapid removal of 10% of the blood volume have been compared in non-pregnant and pregnant anaesthetized rabbits close to term (28 or 29 days gestation). Immediately after the end of haemorrhage the fall in arterial pressure was greater in the pregnant group (27.7 vs. 17.8 mmHg), but as recovery proceeded the difference diminished and by the tenth minute the reduction from pre-haemorrhage levels was similar in pregnant and non-pregnant rabbits. Cardiac output fell by about 30% in both groups and increased only very slightly during the ensuing 10 min. 1 h after section of the carotid sinus and aortic nerves the haemorrhage was repeated. The fall in arterial pressure in the non-pregnant rabbits was now more than doubled (47.2 vs. 17.8 mmHg). By contrast it was little changed in the pregnant rabbits (32.0 vs. 27.7 mmHg). It is concluded that pregnancy diminishes the role of the baroreceptor reflexes in the response of the rabbit to haemorrhage. Other mechanisms, such as an increased compliance of the resistance vessels and/or a more effective chemically mediated vasoconstriction, probably become of more importance to the maintenance of arterial pressure.
在接近足月（妊娠28或29天）的未孕和孕兔中，比较了快速抽取10%血容量后动脉血压和心输出量的变化。出血结束后即刻，孕兔组动脉压下降幅度更大（27.7对17.8 mmHg），但随着恢复过程的进行，差异减小，到第10分钟时，孕兔和未孕兔从出血前水平的降低幅度相似。两组的心输出量均下降约30%，且在随后的10分钟内仅略有增加。切断颈动脉窦和主动脉神经1小时后重复出血。此时未孕兔的动脉压下降幅度增加了一倍多（47.2对17.8 mmHg）。相比之下，孕兔的动脉压变化不大（32.0对27.7 mmHg）。结论是，妊娠减弱了压力感受器反射在兔对出血反应中的作用。其他机制，如阻力血管顺应性增加和/或化学介导的血管收缩更有效，可能对维持动脉压变得更为重要。
