What physiological effect does a Beta 1 agonist have on the heart?

A Beta 1 agonist primarily binds to beta-1 adrenergic receptors in the heart, leading to an increase in heart rate, which is known as positive chronotropic effect. This occurs because activation of these receptors enhances the depolarization rate of the sinoatrial (SA) node, where the electrical impulses that initiate heartbeats are generated. Additionally, beta-1 agonists also increase cardiac contractility, or the force of heart muscle contractions, which is a positive inotropic effect.

This action is essential in situations where increased cardiac output is necessary, such as during physical activity or in response to stress. While vasodilation is more associated with beta-2 agonists, Beta 1 agonists specifically influence heart rate and contractility. Therefore, the increase in heart rate through the stimulation of beta-1 receptors in the heart is a key physiological effect.