Which statement describes how contractility would change dP/dt max when beta-adrenergic stimulation is applied?

• A. Increase.
• B. Decrease.
• C. No change.
• D. First increase then decrease.

Answer: (A)

Beta-adrenergic stimulation increases contractility by boosting intracellular calcium during systole, through the Gs-cAMP-PKA pathway that enhances calcium entry and release from the sarcoplasmic reticulum. More calcium strengthens and speeds up cross-bridge cycling, making the ventricle contract more forcefully and rapidly. The maximal rate of pressure rise (dP/dt max) reflects this inotropic state, so it rises when contractility goes up. Therefore, the correct description is that dP/dt max increases. The other possibilities would imply no change, a decrease, or an initial rise followed by fall, which don’t align with the acute inotropic enhancement caused by beta stimulation.