Effects of Carbon Dioxide Inhalation on Hematology,Coagulation,and Serum Clinical Chemistry Values in Rats

Abstract

Blood samples from adult male and female Charles River Cr1:CD® (SD) BR rats were collected at weekly intervals for 4 wk to evaluate the effects of inhalation of an anesthetic dose of carbon dioxide (CO₂) or of a carbon dioxide-oxygen mixture (CO₂/O₂) on hematology, coagulation, and serum biochemistry values. During the first 3 wk of the study, rats were assigned to 1 of 3 groups and were bled from the orbital sinus once weekly. Prior to the blood collection, rats in group 1 were exposed to room air only, rats in group 2 received CO₂/O₂ (approximately 66%:34% CO₂:O₂) by inhalation, and rats in group 3 received 100% CO₂ by inhalation. In the rats exposed to CO₂/O₂ or CO₂, leukocyte counts, lymphocyte counts, and glucose values were higher, and aspartate aminotransferase, creatine kinase, and calcium values were lower compared with those of rats exposed to room air only. Rats exposed to 100% CO₂ had slightly (but statistically significant) lower mean corpuscular hemoglobin concentration when compared with rats exposed only to room air. During week 4, all rats were reassigned to 1 of 2 groups and were bled terminally via closed cardiac puncture following exposure to either CO₂/O₂ or CO₂. Increased lymphocyte counts (males only) and glucose and chloride concentrations were noted for rats exposed to CO₂/O₂ compared with those exposed to CO₂. These alterations reiterate the importance of comparing clinical pathology values to those of concurrent control groups that have experienced blood collection under identical conditions in order to avoid potential errors in the interpretation of data.

Keywords

Clinical pathology hematology clinical chemistry rat blood collection orbital sinus

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