A 50-year-old man is brought to the emergency room complaining of severe dizziness and confusion. He claims to have experienced chest pain and took several nitroglycerin tablets. His current medications include a daily aspirin for heart attack prevention, acetaminophen for headaches, and tadalafil for erectile dysfunction on occasion. He has a blood pressure of 50/20 mmHg and a heart rate of 120 beats per minute. Which of the following cellular changes is most likely responsible for this patient's symptoms?

Question

Quizplus · Accepted Answer

Eductional Objective: The interaction between nitrates and phosphodiesterase inhibitors used to treat erectile dysfunction (tadalafil, sildenafil, and vardenafil) is well known and critical to comprehend. Nitrates are converted to nitric oxide by vascular smooth muscle cells, and nitric oxide acts as a second messenger by increasing intracellular cGMP. Increased cGMP concentration relaxes vascular smooth muscle. Furthermore, phosphodiesterase metabolizes cGMP within cells, so phosphodiesterase inhibitors increase intracellular cGMP. When these drugs are used together, cGMP accumulation in vascular smooth muscle cells due to both increased synthesis (nitrates) and inhibited degradation (PDE inhibitors) causes profound hypotension due to extreme vasodilation.

A 50-Year-Old Man Is Brought to the Emergency Room Complaining