Reaction temperature alters chorzoxazone metabolism in carp (Cyprinus carpio) hepatic microsomes

Abstract

The study aimed to study the influence of different reaction temperatures on the carp (Cyprinus carpio) hepatic CYPs activity. Six groups of carp hepatic microsomes were incubated with probe drug (chorzoxazone) at 5, 10, 15, 20, 25 and 30°C separately. According to the principle of enzyme kinetics theory, the Michaelis constant (K (m)) value and maximum reaction velocity (V (max)) of CYPs (with CZX as probe) were obtained. The CYPs activity at different reaction temperatures was compared. In results, the K (m) values were separately 44.62, 31.35, 26.59, 21.75, 16.39, 29.69 μM, and the V (max) were separately 0.231, 0.234, 0.265, 0.294, 0.315, 0.239 nmol min(-1)mg(-1) at 5, 10, 15, 20, 25, 30°C. Results indicated that the enzyme CYPs activity was much higher at 25°C. It was also demonstrated that reaction temperature could affect the CYPs activity significantly. Therefore, this experiment builded a theoretical basis for the variations of fish pharmacokinetic parameters at different water temperatures and contributed to further research on the influence of water temperature on fish drug metabolism.

Accumulation and clearance of tissue residues and health status of Nile tilapia Oreochromis niloticus (L.) juveniles as influenced by the extended oral oxytetracycline-dosing

“…It is an easily degradable drug but can stay in muscle as metabolites forms or the pond sediment for a certain period (Romero et al 2012;Watts et al 2017). The absorption and elimination period is greatly in uenced by temperature (Li et al 2012). The present study at 22-26°C recorded a dose-dependent OTC-residue increase during the dosing period both in 10 and 20 days trials.…”

“…Further, the safety data on the farmed sh are required as part of the drug registration process in most countries. In sh, the drug metabolism is generally temperature-dependent so also the toxicity, which is greater at higher temperatures (Li et al 2012). Also, the potential effects of medicated feed administration in tropical sh are limited.…”