Epinephrine and acetylcholine each produces dose-related changes in blood pressure, but by different mechanisms:

• Low doses of epinephrine act on beta receptors and decrease blood pressure by vasodilation.
• High doses of epinephrine act on alpha receptors and increase blood pressure by vasoconstriction.
• Low doses of acetylcholine act on muscarinic receptors and decrease blood pressure by vasodilation.
• High doses of acetylcholine act on the nicotinic receptors of the autonomic ganglia and increase blood pressure indirectly through activation of the sympathetic nervous system.

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