Phosphorylation of myosin light chains in perfused rat heart. Effect of adrenaline and increased cytoplasmic calcium ions.
1. 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.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004837:Epinephrine / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D009218:Myosins / Q000302:isolation & purification / Q000378:metabolism*; D010477:Perfusion; D010766:Phosphorylation; D051381:Rats
D009218:Myosins; D002118:Calcium; D004837:Epinephrine