Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Avenida Bandeirantes, 3900 Ribeirão Preto, SP, Brazil.
Respir Physiol Neurobiol. 2010 Aug 31;173(1):47-50. doi: 10.1016/j.resp.2010.06.004. Epub 2010 Jun 17.
The South American lungfish (Lepidosiren paradoxa) has an arterial P(O(2)) (Pa(O(2))) as high as 70-100 mmHg, corresponding to Hb-O(2) saturations from 90% to 95%, which indicates a moderate cardiovascular right to left (R-L) shunt. In hyperoxia (50% O(2)), we studied animals in: (1) aerated water combined with aerial hyperoxia, which increased Pa(O(2)) from 78+/-2 to 114+/-3 mmHg and (2) and aquatic hyperoxia (50% O(2)) combined room air, which gradually increased Pa(O(2)) from 75+/-4 mmHg to as much as 146+/-10 mmHg. Further, the hyperoxia (50%) depressed pulmonary ventilation from 58+/-13 to 5.5+/-3.0 mLBTPSkgh(-1), and Pa(CO(2)) increased from 20+/-2 to 31+/-4 mmHg, while pHa became reduced from 7.56+/-0.03 to 7.31+/-0.09. At the same time, venous P(O(2)) (Pv(O(2))) rose from 40.0+/-2.3 to 46.4+/-1.2 mmHg and, concomitantly, Pv(CO(2)) increased from 23.2+/-1.1 to 32.2+/-0.5 mmHg. R-L shunts were estimated to about 19%, which is moderate when compared to most amphibians.
南美肺鱼（Lepidosiren paradoxa）的动脉血氧分压（Pa(O(2)))高达 70-100mmHg，对应的血红蛋白氧饱和度为 90%-95%，这表明其心血管存在中等程度的右向左分流。在高氧环境（50% O(2)))下，我们研究了以下两种情况下的动物：（1）充氧水联合大气高氧，使 Pa(O(2)))从 78+/-2mmHg 增加到 114+/-3mmHg；（2）水合高氧（50% O(2)))联合室内空气，使 Pa(O(2)))逐渐从 75+/-4mmHg 增加到高达 146+/-10mmHg。此外，高氧（50%）使肺通气从 58+/-13mLBTPSkgh(-1) 降低到 5.5+/-3.0mLBTPSkgh(-1)，Pa(CO(2)))从 20+/-2mmHg 增加到 31+/-4mmHg，而 pHa 从 7.56+/-0.03 降低到 7.31+/-0.09。同时，静脉血氧分压（Pv(O(2)))从 40.0+/-2.3mmHg 升高到 46.4+/-1.2mmHg，同时，Pv(CO(2)))从 23.2+/-1.1mmHg 增加到 32.2+/-0.5mmHg。右向左分流约为 19%，与大多数两栖动物相比处于中等水平。
