Herbert N A, Wells R M G
School of Biological Sciences, The University of Auckland, New Zealand.
J Comp Physiol B. 2002 Dec;172(8):725-31. doi: 10.1007/s00360-002-0303-y. Epub 2002 Oct 16.
It is hypothesised that the visual performance of rainbow trout, Oncorhynchus mykiss, will be impaired by strenuous exercise as a result of metabolic stress (blood lactacidosis) that activates the Root effect and limits the oxygen-carrying capacity of blood flowing to the eye. The ability to resolve high contrast objects on a moving background, as a measure of visual performance, was quantified pre- and post-exercise using the optomotor response. Strenuous exercise induced a metabolic acidosis (8.0 mmol l(-1) blood lactate) and a significant red cell swelling response but no change in the optomotor response threshold (120 min of arc) was observed. Beta-adrenergic blockade (propranolol) abolished post-exercise red cell swelling but optomotor response thresholds were still maintained at 120 min of arc despite a significant blood lactate load (7.8 mmol l(-1)). The choroid rete mirabile of the trout is extremely well developed (rete area:eye area = 0.39) and may maintain visual performance by ensuring a relatively direct supply of oxygen to the central regions of the avascular retina. Exercised fish under beta-adrenergic blockade exhibited an enhanced optomotor response at 240-300 min of arc. Assuming that these responses reflect "tunnel vision", adrenergic regulation of red cell function may preserve a high ocular PO(2) gradient that satisfies the oxygen demand of peripheral retinal cells.
据推测，虹鳟（Oncorhynchus mykiss）的视觉表现会因剧烈运动而受损，这是由于代谢应激（血液乳酸酸中毒）激活了鲁特效应并限制了流向眼睛的血液的携氧能力。作为视觉表现的一种衡量方式，在运动前后使用视动反应对在移动背景上分辨高对比度物体的能力进行了量化。剧烈运动诱发了代谢性酸中毒（血液乳酸浓度为8.0 mmol l(-1)）和明显的红细胞肿胀反应，但未观察到视动反应阈值（120分弧度）有变化。β-肾上腺素能阻断（普萘洛尔）消除了运动后的红细胞肿胀，但尽管血液乳酸负荷显著（7.8 mmol l(-1)），视动反应阈值仍维持在120分弧度。虹鳟的脉络膜奇异网极为发达（脉络膜面积：眼睛面积 = 0.39），可能通过确保向无血管视网膜的中央区域相对直接地供应氧气来维持视觉表现。在β-肾上腺素能阻断下的运动鱼在240 - 300分弧度时表现出增强的视动反应。假设这些反应反映了“管状视野”，红细胞功能的肾上腺素能调节可能会维持一个高的眼内氧分压梯度，以满足周边视网膜细胞的氧气需求。
