tachycardia

Good afternoon, I am currently very confused about adrenergic drugs and their toxic effects particularly reflex bradycardia or tachycardia. Will someone please clarify the mechanism of this? Here's what I understand thus far: 1) Decrease in blood pressure can stimulate baroreceptor...

So I got a Kaplan question saying that Ach administration INCREASES heart rate? I now get the mechanism they're going for. Ach --> peripheral vasodilation --> reflex tachycardia. But...like...what about the M2 muscarinic receptor on the heart?? Wouldn't Ach directly cause bradycardia by acting...