Characterizing Tissue Enzyme Activities in the Marine Toad (Rhinella marina)

Abstract Plasma biochemistry tests are routine diagnostic tools in veterinary medicine that require an understanding of the enzyme activity profiles of individual organs for accurate interpretation. Tissue enzyme activity has been found to vary among and within taxa and has not been described in the marine toad (Rhinella marina). This study measured enzyme activities in the plasma, liver, heart, skeletal muscle, gastrointestinal system, kidney, and pancreas of five marine toads, to evaluate the tissue specificity of analytes commonly included on plasma biochemical analysis. In the marine toad, alanine transaminase (ALT) and aspartate transaminase activities were not specific to one organ, with minimal ALT activity measured in any organ tissue. Alkaline phosphatase activity was significantly higher in heart tissues and gamma-glutamyltransferase (GGT) activity was significantly higher in pancreatic tissues than in all other organ tissues, and plasma. GGT activity in the kidney was also significantly higher than that found in plasma, but not all other tissues. Amylase and lipase were highest in the plasma. Creatine phosphokinase and lactate dehydrogenase (LDH) were specific to skeletal muscle, with significant LDH activity also found in cardiac tissue. This information will be vital to the interpretation of plasma biochemistry analysis in the marine toad and shows similarities to tissue enzyme activity in the Cuban treefrog (Osteopilus septentrionalis), suggesting extrapolation to other anurans is possible.