Arteriovenous shunting in experimental liver cirrhosis in rats

The extent of systemic arteriovenous shunting (arteriovenous anastomotic blood flow) was assessed in rats with experimental liver cirrhosis and control rats by injecting 15 micron microspheres into the left ventricle and measuring the percentage of injected spheres trapped in the pulmonary circulation. Cirrhotic rats with body temperature maintained at 38 degrees C were found to have increased trapping of microspheres in the pulmonary bed when compared with control rats studied under similar conditions (8.2% +/- 2.2% vs. 3.6% +/- 0.8%, P less than 0.05). The extent of arteriovenous shunting was also measured in control rats maintained at various body temperatures (34 degrees to 40 degrees C) with and without prior alpha-adrenergic blockade with phenoxybenzamine (0.1 mg/kg). Both body warming and alpha-adrenergic blockade independently increased the extent of arteriovenous shunting. In cirrhotic rats, body warming also increased shunting. However, in contrast to findings in control rats, alpha-adrenergic blockade did not further increase shunting in cirrhotic rats warmed to 40 degrees C. Moreover, the degree of shunting after combined body warming and alpha-adrenergic blockade was similar in cirrhotic and control rats. Our results indicate that increased peripheral arteriovenous shunting occurs in this model of experimental cirrhosis, and that the increased shunting may be related to altered physiologic regulation of arteriovenous anastomotic blood flow.