Key Points
- To determine the extent and timing of myosin P light chain and troponin I phosphorylation in perfused beating rabbit hearts exposed to adrenaline or ischemia.
- Utilized two-dimensional electrophoresis combined with a sample preparation technique designed to eliminate endogenous protein phosphatase activity.
- Assessed phosphorylated and unphosphorylated protein fractions in perfused beating rabbit hearts and ventricular tissue from rabbits, guinea pigs, and cows.
- Approximately 25% of the ventricular myosin P light-chain fraction was phosphorylated under baseline conditions both in vivo and in perfused beating hearts.
- Adrenaline administration induced a slight increase in the phosphorylation of both myosin P light chain and troponin I, peaking after the maximum inotropic response.
- Myocardial ischemia in the absence of adrenaline produced an increase in P light chain phosphorylation comparable to that seen with adrenaline.
Structured PICO
Does adrenaline alter the phosphorylation of the P light chain of myosin and troponin I in the perfused rabbit heart?
PPopulationPerfused rabbit beating heart (and ventricles of rabbit, guinea pig, and cow)
CComparatorBaseline/absence of adrenaline
OOutcomeExtent of phosphorylation of the P light chain of myosin and troponin Isurrogate
Adrenaline induces a slight, delayed increase in the phosphorylation of the P light chain of myosin and troponin I in the perfused rabbit heart, peaking after the maximal inotropic response.