Hemodynamic characterization of conscious and ketamine-anesthetized bile duct-ligated rats

The present study was conducted to characterize the hemodynamic alterations in common bile duct-ligated (CBDL) rats under ketamine anesthesia and in the awake restrained state. Hemodynamic studies using the radioactive microspheres technique were performed 17.6 ± 0.6 (SE) days after bile duct ligation or sham operation. CBDL rats had lower mean arterial pressure, reduced systemic and renal resistance, and increased renal blood flow compared with sham-operated rats. This was found both in the conscious and anesthetized states. Anesthetized CBDL rats had higher portal pressure (13.2 ± 0.5 vs. 9.2 ± 0.4 mmHg; P < 0.001) and lower splanchnic arteriolar resistance (15.4 ± 1.3 vs. 26.8 ± 4.6 mmHg·ml^-1·min·100 g body wt; P < 0.05) than sham-operated rats. Portosystemic shunting was 52.3 ± 11.7% in CBDL and negligible in sham-operated rats. The last three parameters could not be measured in conscious animals. Total peripheral resistance was lower in the conscious than in the anesthetized state, diverting a higher fraction of cardiac output at the expense of splanchnic organs and leading to a significant reduction of portal venous inflow in sham-operated but not in CBDL rats [3.36 ± 0.47 vs. 5.38 ± 0.65 (P < 0.05) and 5.33 ± 0.58 vs. 6.34 ± 0.37 ml·min^-1·100 g body wt^-1 (P = NS), respectively]. These findings indicate that CBDL and normal rats respond differently to anesthesia and restraint. Because the restrained state is stressful and studies in anesthetized animals are technically simpler, provide additional information such as portal pressure and portosystemic shunting, and diminish animal suffering, we suggest that hemodynamic studies in rats, using the microsphere technique, should be preferably performed under ketamine anesthesia.