If a patient undergoing coronary artery bypass grafting (CABG) experiences unexpected bronchoconstriction and hypotension immediately after protamine administration (to reverse heparin), which mechanism explains the most likely cause?

💡 Explanation

Protamine can trigger non-immunological mast cell degranulation, resulting in the release of histamine and other mediators that cause bronchoconstriction and hypotension. This is because protamine, being a cationic peptide, interacts directly with mast cells, therefore inducing degranulation, rather than complement activation or direct myocardial effects.

• Why does asthma-induced bronchoconstriction worsen upon allergen exposure, even with a beta-agonist inhaler?
• A patient with a rare genetic defect lacks functional T-helper cells. Which immunological outcome is most likely, hindering antibody production against a novel viral infection?
• What distinguishes why bone mineral density increases with resistance exercise differently than with increased dietary calcium?
• Why does chronic hyperextension at the knee joint increase the risk of anterior cruciate ligament (ACL) injury during rapid deceleration?
• Why does a neuron's action potential propagate unidirectionally away from the soma, rather than bidirectionally?
• What causes increased susceptibility to autoimmune diseases when regulatory T cells (Tregs) are functionally impaired during early childhood development?