As humans, we have receptors for two kinds of beta adrenergic compounds such as catecholamines. cardiac muscle cells have beta 1 receptors that promote increased heart rate. some drugs that slow heart rate are called beta blockers. smooth muscle cells, however, have beta 2 receptors which mediate muscle relaxation. blockers of these effects are sometimes used to treat asthma. the use of beta 2 antagonist drugs may be useful in asthma because:

Because a drug acts on one type of receptor does not mean that it will act on another type.

Explanation:

As humans, we have receptors for two kinds of beta adrenergic compounds such as catecholamines. Cardiac muscle cells have beta 1 receptors that promote increased heart rate. Some drugs that slow heart rate are called beta blockers. Smooth muscle cells, however, have beta 2 receptors which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma. The use of beta 2 antagonist drugs may be useful in asthma because a drug acts on one type of receptor does not mean that it will act on another type.