Participation of phosphoryl transfer network on branchial energetic imbalance of matrinxã (Brycon amazonicus) exposed to air: Notable involvement of creatine kinase

Abstract

Concerns about common aquaculture procedures have been currently raised, including air exposure, since usually they cause a variable degree of stress and contribute to fish mortality. Energetic alterations during exposure to air have been extensively reported, but their effects linked to phosphoryl transfer network, an essential network of enzymes to precise coupling of the adenosine triphosphate (ATP)-production and ATP-consuming process for maintenance of bioenergetic homeostasis remain unknown. Thus, the aim of this study was to evaluate whether the phosphoryl transfer network could be a pathway involved in the bioenergetic imbalance of matrinxã (Brycon amazonicus) exposed to air. Branchial cytosolic and mitochondrial creatine kinase (CK) activities were significantly lower at 30 and 60 min post-stress in fish subjected to air exposure than in the control group. Branchial ATP content and sodium‑potassium pump (Na+, K+-ATPase) activity were significantly lower at 30 and 60 min post-stress in fish subjected to air exposure than in the control group, while reactive oxygen species (ROS) and lipid peroxidation levels were significantly higher in the same moments in fish subjected to air exposure than in the control group. No significant difference was observed between groups or over the time regarding adenylate kinase and pyruvate kinase activities. Based on these data, impairment of CK activity elicited by air exposure disrupted branchial energetic balance via reduction on ATP availability in the gills and provoked impairment of Na+, K +ATPase activity, which appears to be mediated by ROS overproduction and lipid peroxidation.