Circulating catecholamines will have what effect on conduction velocity?

Circulating catecholamines will have what effect on conduction velocity?

• A. Decrease
• B. Increase
• C. No effect
• D. Variable

Answer: (B)

Circulating catecholamines boost sympathetic signaling in the heart, which speeds electrical conduction. They act on β1-adrenergic receptors to raise cAMP and activate PKA, phosphorylating key ion channels. This increases inward calcium current in nodal tissue and enhances sodium/calcium currents overall, speeding up the upstroke of the action potential. The AV node relies on calcium currents for conduction, so this calcium channel enhancement particularly speeds AV conduction. The net effect is faster conduction velocity, i.e., a positive dromotropic effect.

Circulating catecholamines boost sympathetic signaling in the heart, which speeds electrical conduction. They act on β1-adrenergic receptors to raise cAMP and activate PKA, phosphorylating key ion channels. This increases inward calcium current in nodal tissue and enhances sodium/calcium currents overall, speeding up the upstroke of the action potential. The AV node relies on calcium currents for conduction, so this calcium channel enhancement particularly speeds AV conduction. The net effect is faster conduction velocity, i.e., a positive dromotropic effect.