Forster M E, Davison W, Axelsson M, Farrell A P
Department of Zoology, University of Canterbury, Christchurch, New Zealand.
Respir Physiol. 1992 Jun;88(3):373-86. doi: 10.1016/0034-5687(92)90010-t.
Simultaneous measurements of cardiac output (Q), blood pressures and blood gases were made in the hagfish, Eptatretus cirrhatus, during exposure to hypoxia. The partial pressure of oxygen in the medium (PIO2) was reduced from 20.7 kPa to 8.0 kPa and then lowered to 5.3 kPa. At a PIO2 of 5.3 kPa there was a 40% increase in Q. Part of the increase may have been due to the increased activity of the animal at low PIO2. In recovery, when the animals were inactive, Q continued to rise to 160% of the control values. At 5.3 kPa, oxygen consumption (as determined by the Fick principle) fell to 29% of the normoxic value and was associated with increased branchial vascular resistance (Rg) and an increased diffusion limitation of the gills (Ldiff). Adrenaline increased heart rate and aortic blood pressures. Increased Rg and Ldiff could be provoked in normoxia by the injection of the beta-adrenergic blocking drug propranolol. We suggest that catecholamines may be involved in the tonic control of gill vasomotor tone.
在对盲鳗（Eptatretus cirrhatus）进行低氧暴露实验期间，同时测量了其心输出量（Q）、血压和血气。将环境中氧气的分压（PIO2）从20.7 kPa降至8.0 kPa，然后再降至5.3 kPa。在PIO2为5.3 kPa时，心输出量增加了40%。心输出量增加的部分原因可能是动物在低PIO2时活动增加。在恢复阶段，当动物不活动时，心输出量继续上升至对照值的160%。在5.3 kPa时，耗氧量（根据菲克原理测定）降至常氧值的29%，并伴有鳃血管阻力（Rg）增加和鳃部扩散限制（Ldiff）增大。肾上腺素会使心率和主动脉血压升高。在常氧状态下注射β-肾上腺素能阻断药物普萘洛尔可引发Rg和Ldiff增加。我们认为儿茶酚胺可能参与了鳃血管运动张力的紧张性调节。
