Hepatic blood volume responses and compliance in cats with long-term bile duct ligation

Hepatic capacitance responses were compared in sham-operated and 14-day bile duct-ligated cats under pentobarbital anesthesia. Both groups were subjected to splenectomy and had the anterior hepatic nerve plexus sectioned to allow stimulation; the posterior plexus was intact. Blood volume compensation for hemorrhage was reduced in the bile duct ligation group compared with the control group: The liver compensated for 20.1% and 10.6% of blood loss, respectively. Portal hypertension did not exist and hepatic compliance was unaltered despite the presence of severe biliary hyperplasia, portal tract distortion and fibrosis. The capacitance responses to hemorrhage in the bile duct ligation group were accounted for entirely by a passive compliant response to reduced portal pressure, whereas the sham surgery group showed an additional active component. Responses of liver volume and venous resistance to norepinephrine were normal, but responses to nerve stimulation were reduced. The nerve dysfunction was not universal; reflex arterial blood pressure response to carotid occlusion was normal. The data suggest that hepatic blood volume responses to hemorrhage is mediated by passive compliant responses to reduced portal pressure (stressed volume) and active responses (unstressed volume) to nerve stimulation but that long-term bile duct ligation produces selective hepatic neuropathy resulting in loss of the active component.