Epinephrine has positive lusitropy.

Epinephrine has positive lusitropy.

• A. True
• B. False
• C. It has no lusitropy
• D. It causes negative lusitropy

Answer: (A)

Positive lusitropy means faster ventricular relaxation during diastole. Epinephrine, acting on beta-1 receptors, raises cAMP and activates PKA. This leads to phosphorylation of phospholamban, relieving its inhibition of SERCA, so calcium is sequestered into the sarcoplasmic reticulum more quickly during diastole. That faster calcium clearance shortens the time needed for relaxation, producing a quicker, more efficient diastolic period. PKA also phosphorylates troponin I, reducing calcium sensitivity of the myofilaments, which further aids relaxation. So, epinephrine enhances both systolic performance and diastolic relaxation, giving positive lusitropy.

Positive lusitropy means faster ventricular relaxation during diastole. Epinephrine, acting on beta-1 receptors, raises cAMP and activates PKA. This leads to phosphorylation of phospholamban, relieving its inhibition of SERCA, so calcium is sequestered into the sarcoplasmic reticulum more quickly during diastole. That faster calcium clearance shortens the time needed for relaxation, producing a quicker, more efficient diastolic period. PKA also phosphorylates troponin I, reducing calcium sensitivity of the myofilaments, which further aids relaxation. So, epinephrine enhances both systolic performance and diastolic relaxation, giving positive lusitropy.