Short communicationGuanfacine enhances cardiac acetylcholine release with little effect on norepinephrine release in anesthetized rabbits

- Microdialysis technique was applied to the rabbit's atrial myocardium.
- Guanfacine significantly increased cardiac vagal acetylcholine release.
- Guanfacine hardly affected cardiac sympathetic norepinephrine release.

An α2A-adrenergic agonist guanfacine improves autonomic imbalance in attention-deficit hyperactivity disorder, suggesting that it may be useful to correct autonomic imbalance in chronic heart failure (CHF) patients. To investigate the effects of guanfacine on cardiac autonomic nerve activities, a microdialysis technique was applied to anesthetized rabbit heart. Acetylcholine (ACh) and norepinephrine (NE) concentrations in atrial dialysates were measured as indices of cardiac autonomic nerve activities. Guanfacine at a dose of 100 μg/kg significantly decreased heart rate and increased dialysate ACh concentration without decreasing sympathetic NE release. Guanfacine may be useful for vagal activation therapy in CHF patients.

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