| Abstract: | It was demonstrated that under normal conditions calmodulin and exogenous 3':5'-AMP-dependent protein kinase considerably active Ca2+ transport by sarcoplasmic reticulum of rabbit myocardium; a combined action of these compounds produces an additive effect. The protein-inhibitor of 3':5'-AMP-dependent protein kinase and trifluoroperazine eliminate the activating effect of 3':5'-AMP-dependent protein kinase; in addition, trifluoroperazine decreases significantly the basal level of Ca2+ uptake. The 3':5'-AMP-dependent activation of Ca2+ transport becomes apparent after Ca2+-calmodulin-dependent phosphorylation of FSR membrane proteins. In toxico-allergic myocarditis calmodulin and 3':5'-AMP-dependent protein kinase do not activate the low level of Ca2+ uptake. No differences were observed between the action of calmodulin and 3':5'-AMP-dependent protein kinase isolated from normal and pathological rabbit heart. A conclusion is drawn that the decrease of Ca2+ transport is due to the impairment of Ca2+-calmodulin and 3':5'-AMP-dependent phosphorylation in sarcoplasmic reticulum membranes. |
