1. The pressor and heart rate response to angiotensin II, noradrenaline, isoprenaline, tyramine and β-phenylethylamine were examined before and after bile-duct ligation in conscious trained dogs.
2. The pressor response to angiotensin II was markedly suppressed after bile-duct ligation, although responses to noradrenaline and the indirectly acting sympathomimetic amines were only slightly reduced.
3. Bradycardia, in response to the pressor drugs, and tachycardia, in response to isoprenaline, were unchanged after bile-duct ligation.
4. Refractoriness to the pressor action of angiotensin after chronic bile-duct ligation in the present study is similar to that reported previously by others in patients with liver cirrhosis.
5. No evidence was found in the bile-duct ligated dog to support a role of false neurotransmitters as mediators of the circulatory disturbances associated with liver injury.