What is the expected effect of a Beta 1 antagonist on the cardiovascular system?

A Beta 1 antagonist primarily affects the heart by blocking the action of norepinephrine and epinephrine on Beta 1 adrenergic receptors, which are mainly located in the heart. This blockade reduces the heart rate (negative chronotropic effect) and decreases the force of contraction of the heart muscle (negative inotropic effect). As a result, the overall cardiac output may also decrease. The lowering of heart rate and the decrease in the strength of heart contractions contribute to a reduction in blood pressure (antihypertensive effect).

In this context, the option that mentions blocking calcium influx aligns with the mechanism of action of Beta 1 antagonists, which ultimately leads to decreased heart rate and lower blood pressure. This reflects the pharmacological profile of this class of medications, emphasizing how they modulate the body's response to sympathetic stimulation.

Understanding this mechanism is crucial because it highlights how Beta 1 antagonists are utilized in clinical settings to manage conditions like hypertension, heart failure, and certain arrhythmias, where reducing heart workload is desired.