Abstract
To investigate a suitable blood sampling method for hematology and blood biochemistry in fish toxicology, we compared two methods, blood sampling from the Cuvierian duct with a syringe (CD) and caudal vein puncture (CVP) in red sea bream, Chrysophrys major. The CD method did not require special skill because the Cuvierian duct was externally visible. This method allowed us to obtain blood directly from the vessel without disrupting other tissues. The maximum obtainable blood volume withdrawn by CD method was the same as that by CVP method. Clots were occasionally observed in the blood sampled by CVP method, but not by CD method. Activities of lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) were much higher in the plasma obtained by CVP than by the CD method. The activity of glutamate oxaloacetate dehydrogenase (GOT) in CVP was also higher, but to a lesser extent. The values of LDH, CPK and GOT from CVP were much more variable. The correlation coefficients between these values from CVP were higher. Because CPK and LDH are highly concentrated in the muscle, the concomitant elevation of CPK, LDH and GOT activities from CVP could be caused by a leak of these enzymes from muscle cells disrupted by the inserted needle. No significant differences existed in total blood cells, hemoglobin and other biochemical parameters examined between blood samples obtained from either method. Thus the CD method is considered to be a practical and reliable method for blood biochemistry and hematology in fish toxicology.
