A 44-year-old woman who was previously healthy arrives to the emergency room complaining of left flank discomfort, dysuria, a fever, and chills. Blood pressure is 80/40 mm Hg, the temperature is 38.9 C (102 F), and the pulse is regular at 140 bpm. Tenderness at the left costovertebral angle is visible on physical examination. Laboratory tests show pyuria, bacteriuria, and leukocytosis. Intravenous fluids and empiric broad-spectrum antibiotics are given. A phenylephrine infusion is started because the patient's prolonged hypotension cannot be treated with oral medication. Her heart rate drops to 100/min after some time. Which of the following intracellular alterations is anticipated in this patient in comparison to right before the infusion?

Question

Quizplus · Accepted Answer

Eductional Objective: Phenylephrine raises blood pressure by causing vascular smooth muscle cells to produce more inositol triphosphate, which is mediated by the alpha-1 receptor. In response to the sudden rise in blood pressure, the parasympathetic nervous system becomes more active while the sympathetic nervous system's output is reduced. This results in reduced beta-1 adrenergic and muscarinic-2 receptor-mediated cyclic AMP activity in the heart, which lowers heart rate and myocardial contractility. Reduced inward calcium current in sinoatrial cells contributes to the decrease in heart rate.

A 44-Year-Old Woman Who Was Previously Healthy Arrives to the Emergency