REFINEMENT OF BLOOD-SAMPLING FROM THE SUBLINGUAL VEIN OF RATS

A refined method of repeated blood sampling is described: the tongue o f the anaesthetized rat is pulled forward with the fingers and the sub lingual vein is punctured with a 23 gauge hypodermic needle. Based on the requirement of a pharmacokinetic study, 0.5 or 1 mi of blood was c ollected 7 times at 0, 0.5, 1, 2, 4, 8 and 24 h. The degree of sufferi ng was judged by determining the body weight and food and water consum ption. All animals showed an increase in body weight already after 24 h and, therefore, the method of collecting blood from the sublingual v ein can be recommended for repeated blood sampling. The haematological evaluation of groups of animals with differing body weight showed tha t sample volumes of up to 15% of the total blood volume lead to haemat ocrit values of approximately 40%. A remarkable initial drop in white blood cell counts followed by a marked rise 2 h after first sampling t o values partly above the pre-test could not be directly related to th e extracted blood volume.