Endothelium-dependent relaxations in canine coronary arteries are enhanced in early heart failure and persist in recovery.

Abstract

In vitro coronary artery responsiveness to noradrenaline, phenylephrine, and BHT-920 together with functional relaxation to acetylcholine was assessed in dogs at the early onset of pacing-induced heart failure (1 week) and in dogs recovered from heart failure (3 weeks paced, followed by 4 weeks discontinued pacing). alpha-Adrenoceptor stimulation produced contractile responses that were unaltered in early congestive heart failure and recovery. Contractions to noradrenaline and BHT-920 were always less than those produced by phenylephrine. Endothelium-intact arteries demonstrated relaxations in response to noradrenaline and BHT-920, but not phenylephrine. Relaxations to noradrenaline were enhanced 24% in early heart failure and 47% following recovery from heart failure, compared with control. BHT-920 produced relaxations that were augmented 21 and 76% in early heart failure and recovery, respectively. Contractile sensitivity to noradrenaline increased 5-fold in early heart failure and was not different in recovery, compared with control. Contractile sensitivity to BHT-920 and phenylephrine was unaltered throughout. Acetylcholine produced relaxations that were increased 21% in early heart failure and 13% after recovery from congestive heart failure. Furthermore, acetylcholine sensitivity was significantly enhanced in early heart failure and recovery. The current study reveals a progressive adaptation of the coronary endothelium in congestive heart failure, possibly directed towards protection against excessive vasoconstriction due to circulating catecholamines.

• Authors: G Larosa, P W Armstrong, C Forster
• Journal: Canadian journal of physiology and pharmacology (Can J Physiol Pharmacol) Vol. 72 Issue 10 Pg. 1148-54 (Oct 1994) ISSN: 0008-4212 [Print] Canada
• PMID: 7882178 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Adrenergic alpha-Agonists
• Azepines
• Phenylephrine
• talipexole
• Acetylcholine
• Norepinephrine

Topics

• Acetylcholine (pharmacology)
• Adaptation, Physiological
• Adrenergic alpha-Agonists (pharmacology)
• Animals
• Azepines (pharmacology)
• Coronary Vessels (metabolism, physiopathology)
• Dogs
• Dose-Response Relationship, Drug
• Endothelium, Vascular (drug effects, metabolism)
• Heart Failure (physiopathology)
• In Vitro Techniques
• Norepinephrine (pharmacology)
• Phenylephrine (pharmacology)
• Vasodilation (drug effects)