A 40-year-old female with a history of depression and hypertension is brought to the ER after being found obtunded in her apartment. She is hypotensive and bradycardic on physical examination. Intravenous glucagon is administered, and her condition improves. Which of the following intracellular changes is most likely responsible for the improvement in her condition?

Question

A 40-year-old female with a history of depression and hypertension is brought to the ER after being found obtunded in her apartment.  She is hypotensive and bradycardic on physical examination.  Intravenous glucagon is administered, and her condition improves.  Which of the following intracellular changes is most likely responsible for the improvement in her condition?

Quizplus · Accepted Answer

This patient has most likely overdosed on beta blocker medications. Beta blocker overdose causes diffuse non-selective blockade of peripheral beta adrenergic receptors, causing depression of myocardial contractility, bradycardia, and varying degrees of AV block. The result is a low cardiac output state. Glucagon is the drug of choice for beta blocker overdose. Glucagon acts on G protein-coupled receptors, increasing intracellular cAMP and thus increasing the release of intracellular calcium during muscle contraction. This increases heart rate and cardiac contractility. Improvements in heart rate and blood pressure may be observed within minutes. Educational Objective: Patients who have overdosed on beta blockers should be treated with glucagon, which increases heart rate and contractility independent of adrenergic receptors. Glucagon activates G-protein-coupled receptors on cardiac myocytes, causing activation of adenylate cyclase and raising intracellular cAMP. The result is calcium release from intracellular stores and increased sinoatrial node firing.

A 40-Year-Old Female with a History of Depression and Hypertension