Effects of carbon dioxide on serum biochemical patterns and on histopathological changes of organs in rats

The effects of carbon dioxide on serum biochemical patterns and on histopathological changes of organs were studied in male Sprague-Dawley rats which were anesthetized with a mixture of 40% carbon dioxide and 60% oxygen for 3 hr. This level of carbon dioxide is sufficient to maintain rats at an anesthetized level. There were gradual decreased in respiration, body temperature, heart rate, blood pressure and blood pH. At the same time there were significant increases in organ weight (lungs and kidneys), and in exudate to thorax, hematocrit, and serum biochemical patterns (glucose, phosphorus, uric acid, blood urea nitrogen, glutamic pyruvic transaminase, glutamic oxaloacetic transaminase and alpha-hydroxybutyrate dehydrogenase). The weight of the liver, however, decreased slightly. There were minor abnormalities in both gross anatomy and histology (lungs, liver and kidneys). When the rats inhaled ordinary air, they awoke within a few minutes and recovered normal hematological level (pH 7.3, PaO2 120 mmHg and PaCO2 45 mmHg) within 24 hr.