Blunted pressor response to volume load in conscious dogs with chronic bile duct ligation.

Dogs with chronic bile duct ligation have a decreased natriuretic response ot an acute extracellular volume expansion. The present investigation was undertaken in order to study the role of hemodynamic factors in causing the decreased natriuretic response to extracellular volume expansion in chronic bile duct ligated dogs. Five trained, conscious dogs were studied before, and 6 weeks after chronic bile duct ligation, each dog serving as its own control. Under basal conditions systemic hemodynamics were normal following chronic bile duct ligation. However, chronic bile duct ligation was associated with a blunted pressor response to extracellular volume expansion. Thus, at peak extracellular volume expansion, chronic bile duct ligated dogs had smaller increase in mean arterial pressure (P less than 0.05), an exaggerated decrease in systemic vascular resistance (P less than 0.05), and similar cardiac output as compared with normal dogs. This blunted pressor response to extracellular volume expansion may contribute to the decreased natriuresis seen following this maneuver in chronic bile duct ligated dogs.