Regulation of sarcoplasmic reticulum calcium release by luminal calcium in cardiac muscle

10.2741/a852 ◽  
2002 ◽  
Vol 7 (4) ◽  
pp. d1454-1463 ◽  
Author(s):  
Sandor Gyorke
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Calcium Release ◽  
Luminal Calcium ◽  
Sarcoplasmic Reticulum Calcium

Direct Measurement of Sarcoplasmic Reticulum Calcium Content Following Isoproterenol or Caffeine Treatment

1997 ◽  
Vol 3 (S2) ◽  
pp. 919-920
Author(s):  
Wendy E. Sweet ◽  
Christine S. Moravec
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Calcium Release ◽  
Calcium Influx ◽  
Calcium Content ◽  
Storage Site ◽  
Calcium Store ◽  
Indirect Methods ◽  
Β Receptor ◽  
Sarcoplasmic Reticulum Calcium

The major storage site for calcium in cardiac muscle is the sarcoplasmic reticulum (SR). It has been shown using indirect methods that the amount of calcium stored in the SR can be altered by various agonists and anesthetics. The only technique to date which directly quantifies the amount of calcium in the SR is Electron Probe Microanalysis (EPMA). Using EPMA, an accurate measurement of the size of the SR calcium store can be made following treatments with known agonists.Isoproterenol (ISO) causes an increased inotropic response in cardiac muscle via the (3-adrenergic pathway. When ISO binds to the (β-receptor on the plasma membrane, it causes the activation of Protein Kinase A (PKA) through a cascade of events. PKA phosphorylates the sarcolemmal calcium channels causing an increase in the rate of calcium influx. PKA also phosphorylates Tnl, which sensitizes the myofilaments to calcium, thereby increasing the rate of calcium release from the myofilaments.

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