What is a characteristic of beta 1 selective beta blockers?

Beta 1 selective beta blockers primarily target beta 1 adrenergic receptors, which are predominantly found in the heart. Their main therapeutic action is to reduce heart rate and myocardial contractility. This property is particularly beneficial in conditions such as hypertension, heart failure, and certain arrhythmias, where controlling heart rate is crucial for patient management.

Choosing the option that states "Lower heart rate" accurately reflects this characteristic. By blocking the beta 1 receptors in the heart, these medications effectively lower the heart's rate of contraction, thereby reducing heart rate and overall cardiac output.

While other options mention respiratory function and bronchospasm, these are more relevant to non-selective beta blockers that affect both beta 1 and beta 2 receptors, where the beta 2 receptors in the lungs can lead to bronchial dilation. Beta 1 selective blockers minimize risks such as bronchospasm, making them safer for patients with respiratory issues. Thus, the focus on lower heart rate clarifies the primary action and benefit of these medications.