A comparison of blood composition in the common carp (Cyprinus carpio L.) using samples obtained from caudal vessels and dorsal aorta cannulae

Blood samples have been taken from chronic cannulae in the dorsal aorta of Carp under anaesthesia and at intervals of 24, 29 and 101 hours later. A few minutes after the 29 hours and 101 hours sampling was completed similar quantities (1 ml) were withdrawn from a caudal vessel. All samples were treated in the same way and determinations made of haematocrit value, total protein, glucose concentration and activity of the following plasma enzymes-acetylcholinesterase (AChE), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and lactic dehydrogenase (LDH). Comparisons between dorsal aorta and caudal samples at 29 hours and 101 hours showed no significant differences for any of the enzyme activities that were tested. However significant (paired "t"-test, P < 0.05) differences were observed for haematocrit and glucose concentration. It is suggested that the higher haematocrit and lower glucose of caudal samples are consistent with the expected differences between arterial and venous blood. Apart from these differences which reflect normal physiological function, values obtained for samples from the two sites were identical. It is concluded that blood sampling from caudal vessels is a satisfactory method to obtain blood for biomonitoring purposes at least for those enzymes commonly used in recent surveys.