Renal accumulation and effects of intraperitoneal injection of extracted microcystins in omnivorous crucian carp (Carassius auratus).

An acute toxicological experiment was designed to characterize the sequence of renal ultrastructural changes with accumulated MCs in crucian carp injected intraperitoneally (i.p.) with extracted microcystins (mainly MC-RR and -LR) at two doses, 50 and 200 μg MC-LReq. kg⁻¹ body weight. Quantitative and qualitative determinations of MCs in the kidney were conducted by HPLC and LC-MS, respectively. MC-RR content in kidney of crucian carp showed a time dose-dependent increase within 48 h post-injection, followed by a sharp decline afterward, while no MC-LR in kidney was detectable throughout the experiment. Ultrastructural changes in the kidney of crucian carp progressed with increasing accumulated MCs and exposure times within 48 h post-injection, whereas renal ultrastructural recovery of crucian carp in the 50 μg MC-LReq. kg⁻¹ dose group was evident at 168 h post-injection. Our ultrastructural observation suggests that the membranous structure is the main action site of MCs in the kidney, among which mitochondria damage in the tubules is clearly an early, and presumably a critically important effect of MCs. The increases in blood urea nitrogen (BUN) and creatinine (CR) in both dose groups further revealed severe impairment occurred in the kidney of crucian carp.