Paradoxical decrease in heart rate with low dose atropine

Paradoxical decrease in heart rate with low dose atropine

Atropine is a drug which blocks the parasympathetic nervous system and increases the heart rate due to the unopposed action of the sympathetic system. But in low doses, atropine can have the opposite effect of increasing the discharge through vagus, the tenth cranial nerve, an important parasympathetic nerve. This can result in a paradoxical decrease in heart rate with low doses of atropine by a vagotonic effect.