Due to altered mental status, a 78-year-old woman is admitted to the hospital. A history of pyelonephritis, type 2 diabetes mellitus, coronary artery disease, and heart failure with a reduced ejection fraction is significant. The temperature is 36.2 C (97.2 F), the blood pressure is 80/50 mm Hg, the pulse rate is 120 beats per minute, and the respirations rate is 24/ minute. On room air, oxygen saturation is 90%. The examination reveals bilateral crackles. Her blood pressure rises and her heart rate falls after she begins appropriate treatment, which includes the administration of norepinephrine infusions. This patient's change in heart rate is most likely due to norepinephrine's effect on which of the following receptors?

Question

Due to altered mental status, a 78-year-old woman is admitted to the hospital. A history of pyelonephritis, type 2 diabetes mellitus, coronary artery disease, and heart failure with a reduced ejection fraction is significant. The temperature is 36.2 C (97.2 F), the blood pressure is 80/50 mm Hg, the pulse rate is 120 beats per minute, and the respirations rate is 24/ minute. On room air, oxygen saturation is 90%. The examination reveals bilateral crackles. Her blood pressure rises and her heart rate falls after she begins appropriate treatment, which includes the administration of norepinephrine infusions. This patient's change in heart rate is most likely due to norepinephrine's effect on which of the following receptors?

Quizplus · Accepted Answer

Eductional Objective: Norepinephrine strongly stimulates alpha-1 receptors, resulting in peripheral vasoconstriction and an increase in systemic vascular resistance and blood pressure. This causes a baroreceptor-mediated reflexive decrease in heart rate, which completely offsets or overrides the norepinephrine-induced direct beta-1-mediated increase in heart rate, resulting in an overall unchanged or slightly decreased heart rate.

Due to Altered Mental Status, a 78-Year-Old Woman Is Admitted