The role of the sympathetic nervous system in atropine-induced tachycardia in conscious cats.

Injection of atropine sulphate induces tachycardia in conscious unrestrained cats. Injection of the same dose of atropine sulphate after a beta-blocking agent is accompanied by less severe tachycardia. We suggest that atropine sulphate-induced tachycardia in conscious cats, and in anaesthetized animals, is linked to changes in sympathetic-vagal balance, to activation of sympathetic centres and obviously to muscarinic antagonistic effects of atropine in sympathetic nerves.