Pneumonectomy in isoflurane-anesthetized rats without tracheal intubation: an experimental model.

INTRODUCTION: A few models for pneumonectomy in rats have been described, and in most of these, anesthesia includes orotracheal intubation, which increases morbidity and mortality and also adds technical complexity. Models without tracheal intubation but with injectable anesthesia are difficult to reproduce, however, and lead to a lengthy postoperative-recovery period with high morbidity and mortality rates. OBJECTIVE: The objective of this study was to describe a simple, safe, and effective experimental model for pneumonectomy in rats without tracheal intubation. MATERIALS AND METHODS: A left-sided pneumonectomy was performed on 26 Sprague-Dawley rats anesthetized by isoflurane applied via a mask without tracheal intubation. To avoid dangerous traction movements, the lung pedicle was ligated en bloc using clips. RESULTS AND DISCUSSION: No rat demonstrated cardiorespiratory depression. Of the 26 rats, 1 was dehydrated and had lost more than 10% of its body weight, resulting in death on the third day after surgery. Total mortality was therefore 3.8%. Mean (standard deviation [SD]) anesthesia duration was 9.8 (1.0) minutes, surgery time was 3.0 (0.6) minutes, and open pneumothorax time was 1.2 (0.3) minutes. Mean (SD) weight loss during the early postoperative period was 4.5% (3.5%). These results were more satisfactory than results obtained using ketamine mixtures as anesthetic agents (ketamine plus xylacine, and ketamine plus diazepam). CONCLUSION: Our model for left-sided pneumonectomy in isoflurane-anesthetized rats does not require endotracheal intubation and is effective, safe, quick, and easily reproducible.

Control of rate and extent of the proliferative response after partial hepatectomy.

To examine the role of the early changes occurring in the liver within the first hours after a partial hepatectomy and in an attempt to demonstrate the involvement of subsequent regulatory mechanisms, the size of the remnant liver was modified at various times and by different surgical techniques. Male Wistar rats were submitted to a two-thirds "temporary partial hepatectomy" produced by a 3-h occlusion of the pedicle of the anterior lobes protected by local hypothermia. Various indexes of cell proliferation ([3H]thymidine uptake and 5-bromo-2'-deoxyuridine and proliferating cell nuclear antigen labeling) were not increased despite a c-myc expression as high as that observed after a two-thirds partial hepatectomy. The temporary partial hepatectomy and a sham operation induced modifications of the hepatocytes, allowing rapid DNA synthesis after a subsequent two-thirds partial hepatectomy. After this initial nonspecific response, the extent of the regenerative response is determined according to the size of the liver mass present approximately from the 10th to the 18th hour after the initial stimulus. For instance, when a one-third partial hepatectomy was converted into a two-thirds partial hepatectomy at the 10th hour, the DNA synthesis at the 24th hour reached the value observed after a straightforward two-thirds partial hepatectomy. Inversely, the regenerative response was significantly reduced when additional liver lobes were connected to neck vessels between the 14th and the 18th hour after a two-thirds partial hepatectomy. In conclusion, the actual liver mass present during the period corresponding to mid- to late G1 appears to control the magnitude of the proliferative response, which is not the simple consequence of the early changes following a partial hepatectomy.