Role of adenosine triphosphate and protein kinase A in the force-frequency relationship in isolated rat cardiomyocytes

The physiological heart rate of rodents is around 4-6 Hz, although a stimulus frequency 1 Hz generally used in isolated cardiomyocytes to study changes the contraction-relaxation cycle cardiac muscle physiology and pathophysiology. Our investigated contraction parameters at 1, 2 4 stimulation, roles ATP protein kinase A (PKA) force-frequency relationship cardiomyocytes. cell intracellular Ca2+ were recorded simultaneously during stimulation by applying pulses 6-8 V amplitude with frequencies Hz. increase caused significant decrease percentage shortening, relaxation times, slowing rate, diastolic levels, but had no effect on transients. Administration N6-benzoyladenosine-3'-5'-cyclic monophosphate (6-BNZ-cAMP) an speed which proportional times. experimental results show that force-stimulus has negative correlation myocytes energy metabolism ?-adrenergic system may be responsible for this relationship.