Role of phospholamban (22,000-dalton protein) in cyclic AMP-mediated control of Ca2+-dependent ATPase of cardiac sarcoplasmic reticulum

1978 ◽  
Vol 10 ◽  
pp. 119
Author(s):  
TADA
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cyclic Amp ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Dependent Atpase

scholarly journals Effect of cyclic AMP-dependent phosphorylation on the reactivity of sulphydryl groups in cardiac sarcoplasmic reticulum

1980 ◽  
Vol 192 (3) ◽  
pp. 867-872 ◽  
Author(s):  
C J Limas
Keyword(s):  
Protein Kinase ◽  
Sarcoplasmic Reticulum ◽  
Cyclic Amp ◽  
Thiol Groups ◽  
Dependent Protein Kinase ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Dependent Atpase ◽  
Dependent Protein ◽  
Sulphydryl Groups ◽  
Atpase Inhibition

Phosphorylation of cardiac sarcoplasmic reticulum by cyclic AMP-dependent protein kinase results in enhanced Ca2+ transport even though Ca2+-dependent ATPase is not a substrate for the kinase. The mechanisms involved in this enhancement are not clear. In the present study, we used the reactivity of sulphydryl groups in the Ca2+-dependent ATPase as an index of conformational change during the Ca2+ transport cycle and examined the effects of protein kinase-catalysed phosphorylation. N-Ethylmaleimide alkylation allowed the distinction of several thiol groups with variable functional significance for the ATPase. A sulphydryl group involved in the formation of the phosphorylated intermediate (EP) of the Ca2+-dependent ATPase was protected by adenosine 5′-[beta, gamma-imido]triphosphate. Reactivity of an additional thiol group was related to EP dephosphorylation and was dependent on Ca2+. The Ca2+ concentration for change in the reactivity of this sulphydryl group and ATPase inhibition occurred within the range for Ca2+ binding to the high-affinity sites. Phosphorylation of cardiac sarcoplasmic reticulum by cyclic AMP-dependent protein kinase resulted in decreased N-ethyl[1-14C]-maleimide binding and the ATPase inhibition; the thiol groups involved in EP dephosphorylation were selectively protected. The results indicate that protein kinase-catalysed phosphorylation results in conformational changes of the ATPase, which renders certain thiol groups inaccessible to N-ethylmaleimide. This conformational change may facilitate functional movements involved in Ca2+ transport.

scholarly journals Differences in Ca2+-management between the ventricle of two species of neotropical teleosts: the jeju, Hoplerythrinus unitaeniatus (Spix & Agassiz, 1829), and the acara, Geophagus brasiliensis (Quoy & Gaimard, 1824)

2009 ◽  
Vol 7 (3) ◽  
pp. 471-478 ◽  
Author(s):  
Monica Jones Costa ◽  
Francisco Tadeu Rantin ◽  
Ana Lúcia Kalinin
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Physiological Role ◽  
Stimulation Frequency ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Heart Frequency ◽  
Geophagus Brasiliensis ◽  
Hoplerythrinus Unitaeniatus

This study analyzed the physiological role of the cardiac sarcoplasmic reticulum (SR) of two neotropical teleosts, the jeju, Hoplerythrinus unitaeniatus (Erythrinidae), and the acara, Geophagus brasiliensis (Cichlidae). While the in vivo heart frequency (fH - bpm) of acara (79.6 ± 6.6) was higher than that of the jeju (50.3 ± 2.7), the opposite was observed for the ventricular inotropism (Fc - mN/mm²) at 12 bpm (acara = 28.66 ± 1.86 vs. jeju = 36.09 ± 1.67). A 5 min diastolic pause resulted in a strong potentiation of Fc (≅ 90%) of strips from jeju, which was completely abolished by ryanodine. Ryanodine also resulted in a ≅ 20% decrease in the Fc developed by strips from jeju at both subphysiological (12 bpm) and physiological (in vivo) frequencies. However, this effect of ryanodine reducing the Fc from jeju was completely compensated by adrenaline increments (10-9 and 10-6 M). In contrast, strips from acara were irresponsive to ryanodine, irrespective of the stimulation frequency, and increases in adrenaline concentration (to 10-9 and 10-6 M) further increased Fc. These results reinforce the hypothesis of the functionality of the SR as a common trait in neotropical ostariophysian (as jeju), while in acanthopterygians (as acara) it seems to be functional mainly in 'athletic' species.

scholarly journals A Theory of the Mechanism of Cerebral Vasospasm and Its Reversal, the Role of Calcium and Cyclic AMP

1976 ◽  
Vol 3 (4) ◽  
pp. 223-226 ◽  
Author(s):  
Eric W. Peterson ◽  
Richard Leblanc
Keyword(s):  
Smooth Muscle ◽  
Subarachnoid Hemorrhage ◽  
Sarcoplasmic Reticulum ◽  
Cyclic Amp ◽  
Smooth Muscle Cell ◽  
Calcium Ion ◽  
Basic Mechanism ◽  
Free Intracellular Calcium ◽  
Intracellular Calcium Ion

SUMMARY:It is proposed that the basic mechanism of vasospasm which sometimes follows subarachnoid hemorrhage is dependent on increased free intracellular calcium ion produced by spasmogens from closely applied extravasated blood. Relaxation of this spasm occurs when the intracellular cyclic AMP levels are raised, resulting in sequestration of calcium ion by the vascular smooth muscle cell sarcoplasmic reticulum.

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