Abstract

Blood urea nitrogen (BUN) elevation in mammals is one indication of impaired renal function. This test, however, is not commonly conducted in fish presumed to be in renal failure, since most of their nitrogenous wastes are eliminated by the gills. We recently examined the effect of gentamicin-induced renal injury on goldfish serum BUN values. Fish were given IP injections of 50 mg/Kg gentamicin. This dose has been repeated used in our laboratory to cause massive tubular necrosis. In addition, we evaluated the effect of gill hyperplasia, induced by copper sulfate exposure in otherwise untreated fish and in fish with gentamicin-induced renal injury. BUN was significantly elevated in all fish exposed to copper, whether or not they had renal injury. BUN values of fish with only gentamicin-induced renal injury (no copper exposure) remained at control levels.