Vagal stimulation causes bradycardia, which can be blocked by
atenolol
atropine
doxazosin
phenylephrine
Bradycardia due to vagal stimulation is elicited by activation of muscarinic receptor in the heart. Atropine, which is an antagonist at M receptors, blocks bradycardia elicited by stimulation of the vagus, including reflex bradycardia due to increases in mean BP caused by vasoconstrictors.
A.N.S.