scholarly journals ATP synthesis by sarcoplasmic reticulum ATPase following Ca2+, PH, temperature, and water activity jumps.

1982 ◽  
Vol 257 (3) ◽  
pp. 1289-1294 ◽  
Author(s):  
L. de Meis ◽  
G. Inesi
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Water Activity ◽  
Atp Synthesis

Functions of selected biochemical systems from the exercised-trained dog heart

1977 ◽  
Vol 42 (3) ◽  
pp. 426-431 ◽  
Author(s):  
L. A. Sordahl ◽  
G. K. Asimakis ◽  
R. T. Dowell ◽  
H. L. Stone
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Transport ◽  
Calcium Uptake ◽  
Atp Synthesis ◽  
Myocardial Cell ◽  
Ruthenium Red ◽  
Mitochondrial Membranes ◽  
Sedentary Control ◽  
Isolated Mitochondria ◽  
Biochemical Systems

Mitochondria and sarcoplasmic reticulum (SR) fractions were isolated from exercised-trained (E-T) and sedentary control dog hearts. Measurements of mitochondrial respiratory functions indicated no changes in energy-producing (ATP synthesis) capacity in mitochondria from E-T compared to control dog hearts. However, the ability of isolated mitochondria from E-T hearts to retain accumulated calcium was markedly decreased compared to controls. Inhibition of mitochondrial rates of calcium uptake with the inhibitor, ruthenium red, revealed fewer binding and/or transport sites in mitochondrial membranes from exercised-trained heart preparations. ATP-dependent binding (- oxalate) and uptake (+ oxalate) of calcium by SR preparations from E-T hearts were unchanged compared to controls. In contrast, significant differences in the rates of release of bound calcium were found in SR isolated from E-T hearts. Total myocardial protein, nucleic acids, and connective tissue levels were unchanged in E-T hearts compared to controls. The results suggest subtle changes are occurring in the energy-utilizing mechanism(s) involving calcium transport of the myocardial cell during exercise training. These changes may be related to alterations in the performance of the exercised-trained heart.

scholarly journals Effect of temperature on the reversal of the calcium ion pump in sarcoplasmic reticulum

1980 ◽  
Vol 186 (2) ◽  
pp. 461-467 ◽  
Author(s):  
M G P Vale ◽  
A P Carvalho
Keyword(s):  
Activation Energy ◽  
Sarcoplasmic Reticulum ◽  
Calcium Ion ◽  
Atp Synthesis ◽  
Effect Of Temperature ◽  
Coupling Mechanism ◽  
Ion Pump ◽  
Transition Temperatures ◽  
Arrhenius Plots ◽  
Break Points

Sarcoplasmic-reticulum vesicles were actively loaded with Ca2+ in the presence of phosphate, and the ADP-induced Ca2+ efflux and ATP synthesis were measured as a function of temperature. Arrhenius plots show break points for both processes at about 18 and 37 degrees C. Between 18 and 37 degrees C, Ca2+ efflux and ATP synthesis occur with an activation energy of 67.2-71.4 kJ/mol, whereas it is about 189-210 kJ/mol for temperatures below 18 degrees C. Above 37 degrees C, the rates of ADP-induced Ca2+ release and of ATP synthesis sharply decline until the temperature reaches about 42 degrees C. Above this temperature, the Ca2+ efflux increases again even in absence of ADP, although the synthesis of ATP is inhibited, which reflects leakiness of the vesicles. The results show that the transition temperatures for ADP-induced Ca2+ efflux and for ATP synthesis resemble those for active Ca2+ uptake, which indicates that the same coupling mechanism is involved during the inward and outward Ca2+ translocations across the membrane.

scholarly journals Sequential reactions in Pi utilization for ATP synthesis by sarcoplasmic reticulum.

1979 ◽  
Vol 254 (19) ◽  
pp. 9464-9468
Author(s):  
R.M. Chaloub ◽  
H. Guimaraes-Motta ◽  
S. Verjovski-Almeida ◽  
L. de Meis ◽  
G. Inesi
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Atp Synthesis ◽  
Sequential Reactions
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