Why the study?
Does adrenaline or increased calcium alter phosphorylation of myosin light chains in perfused rat hearts?
Does adrenaline or increased calcium alter phosphorylation of myosin light chains in perfused rat hearts?
Phosphorylation of P-light chains does not appear to mediate the action of inotropic agents in the heart.
Findings in perfused rat hearts do not support P-light chain phosphorylation mediating inotropy; leaves open its role in other models or species.
A method was developed for the isolation of essentially pure myosin light chains from perfused rat heart. The phosphorylation of the P-light chains was estimated by hydrolysis and measurement of phosphate released, by electrophoresis in 8 M-urea and by 32P incorporation in perfusion with [32P]Pi. 2. In control perfusions there was 0.5-0.6 mol of phosphate/mol of P-light chain. This was not changed by perfusion with 5 microM-adrenaline for 10-40s. Perfusion for 1 min with medium containing 7.5 mM-CaCl2, or for 30s with medium containing 118 mM-KCl, also did not change the phosphorylation of P-light chains. 3. It is concluded that phosphorylation of P-light chains is not important in mediating the action of inotropic agents in the heart.
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Jeacocke et al. (1980) studied this question.
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