Task: Answer Verification
Input (English): Question: Does a Single Protein Kinase A or Calmodulin Kinase II Site Control the Cardiac Pacemaker Ca2+ Clock?
Answer: SR Ca(2+) depletion reduces HR and SR Ca(2+) repletion restores physiological SANC rate responses, despite CaMKII inhibition. PKA and CaMKII do not affect HR by a unique target site governing SR Ca(2+) uptake or release. HR acceleration may require an SR Ca(2+) content threshold.
Output (English): no