比較頭足類動物的鰓部對於酸與氨的調節運輸機轉

Abstract

卓越的運動能力與補食技巧是頭足類動物成為海洋中頂尖掠食者的關鍵，根據棲地與行為模式，頭足類動物可區分為爬行移動（例如：章魚）以及噴射移動（例如：烏賊）等運動模式。這些模式可能導致頭足類動物發展出不同的代謝、酸鹼與氨的調節機制。本研究發現普通章魚（Octopus vulgaris）血液中的含氨濃度是萊氏擬烏賊 (Sepioteuthis lessoniana) 的十倍以上；然而，萊氏擬烏賊往體內運送氨的速率卻是普通章魚的兩倍以上。此外，利用離體灌流的藥理實驗發現：章魚的鰓表皮細胞，會同時運用主動與被動運輸模式進行酸與氨的調節；然而萊氏擬烏賊的鰓表皮細胞僅會運用主動運輸維持體液恆定。根據以上結果我推論：頭足類動物會因為棲地與運動型態的差異，導致產生不同的代謝、酸與氨等調節機制。

Advanced neural systems and athletic swimming mode enable cephalopods to behave as apex predators in the ocean system. According to their habitats and life styles, they can be divided into crawl and jet-propulsion behavior patterns, thus resulting diverse mechanisms of acid-base and ammonia regulations. In this study, I observed that common octopus (Octopus vulgaris) could accumulate ammonia in blood 10 times higher than bigfin reef squid (Sepioteuthis lessoniana). Moreover, ammonia transport rate (circulating from ctenidial veins to body tissue) in S. lessoniana is two times faster than that of O. vulgaris. Inhibition of apical and basolateral Na+/H+ exchangers (NHEs) by ethylisopropyl amiloride (EIPA) showed significant disruption of H+ and ammonia excretory processes in gills of common octopus, but not in squid. However, inhibition of vacuolar-type H+-ATPase (VHA) by bafilomycin significantly disrupts H+ and ammonia excretion in gills of both animals. Accordingly, jet-propulsion squids prefer active transport for acid/NH4+ transport, while crawling octopus utilize both passive and active transport for homeostasis. Thus, squids may have developed more efficient ammonia-excretory machinery than octopus to avoid nitrogenous toxic effects in blood.