Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada.
Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Comp Biochem Physiol A Mol Integr Physiol. 2022 Mar;265:111123. doi: 10.1016/j.cbpa.2021.111123. Epub 2021 Nov 29.
The basic respiratory gas and acid-base conditions inside the lumen of the gastrointestinal tract (GIT) and blood draining the tract are largely unestablished in teleost fishes after feeding, though there have been some recent novel discoveries on freshwater rainbow trout (Oncorhynchus mykiss) and seawater English sole (Parophrys vetulus). The present study examined in greater detail the gas (PO, PCO, PNH) and acid-base profiles (pH, [HCO], total [ammonia]) in the lumen of the stomach, the anterior, mid, and posterior intestine, as well as the venous drainage (subintestinal and/or hepatic portal vein) of the GIT in these two species 20 h post-feeding. Both species had high PCO, PNH, and total [ammonia], and low PO (virtual anoxia) in the lumens throughout all sections of the GIT, and high [HCO] in the intestine. Total [ammonia], PNH, and [HCO] increased from anterior to posterior intestine in both species. P. vetulus had higher intestinal total [ammonia] and lower [HCO] than O. mykiss post feeding, but total [ammonia] was much higher in the stomach of O. mykiss. Despite the extreme conditions in the lumen, both arterial and venous blood showed relatively lower PCO, total [ammonia] and higher PO, implying limited equilibration between the two compartments. The higher [HCO] and lower total [ammonia] in the intestinal lumen of the freshwater O. mykiss than the seawater P. vetulus suggest the need for future comparative studies using conspecifics fed identical diets but acclimated to the two different salinities in order to understand the potential role of environmental salinity and associated osmoregulatory processes underlying these differences.
在进食后，鱼类胃肠道（GIT）管腔和引流血液的基本呼吸气体和酸碱条件在很大程度上尚未确定，尽管最近在淡水虹鳟（Oncorhynchus mykiss）和海水牙鲆（Parophrys vetulus）上有一些新的发现。本研究更详细地研究了这两种鱼类进食 20 小时后，胃、前、中、后肠管腔以及 GIT 静脉引流（肠系膜和/或肝门静脉）中的气体（PO、PCO、PNH）和酸碱状况（pH、[HCO]、总[氨]）。这两种鱼类在 GIT 的所有肠段管腔中均具有高 PCO、PNH 和总[氨]以及低 PO（虚拟缺氧），且在肠道中具有高[HCO]。在这两种鱼类中，总[氨]、PNH 和[HCO]从肠前段向后段逐渐增加。与 O. mykiss 相比，P. vetulus 进食后具有更高的肠道总[氨]和更低的[HCO]，但 O. mykiss 的胃中总[氨]更高。尽管管腔条件极为恶劣，但动脉和静脉血均显示出相对较低的 PCO、总[氨]和较高的 PO，这表明两个隔室之间的平衡有限。淡水 O. mykiss 的肠道管腔中的[HCO]较高而总[氨]较低，表明需要使用相同饮食喂养但适应两种不同盐度的同种鱼类进行未来的比较研究，以了解环境盐度和相关渗透调节过程在这些差异中的潜在作用。
