Ca2+ sparks and Ca2+ waves in saponin-permeabilized rat ventricular myocytes.
1. We carried out confocal Ca2+ imaging in myocytes permeabilized with saponin in 'internal' solutions containing: MgATP, EGTA and fluo-3 potassium salt. 2. Permeabilized myocytes exhibited spontaneous Ca2+ sparks and waves similar to those observed in intact myocytes loaded with fluo-3 AM. 3. In the presence of 'low' [EGTA] (0.05 mM), Ca2+ waves arose regularly, even at relatively low [Ca2+] (50-100 nM, free). Increasing [EGTA] resulted in decreased frequency and propagation velocity of Ca2+ waves. Propagating waves were completely abolished at [EGTA] > 0.3 mM. 4. The frequency of sparks increased as a function of [Ca2+] (50-400 nM range) with no sign of a high affinity Ca2+-dependent inactivation process. 5. The rate of occurrence of Ca2+ sparks was increased by calmodulin and cyclic adenosine diphosphate-ribose (cADPR).
Lukyanenko
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V
Department of Physiology, Texas Tech University Health Sciences Center, Lubbock 79430, USA.
Gyorke
S
S
D000246:Adenosine Diphosphate Ribose / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology / Q000502:physiology*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002147:Calmodulin / Q000502:physiology; D002463:Cell Membrane Permeability / Q000502:physiology; D002469:Cell Separation; D003600:Cytosol / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018613:Microscopy, Confocal; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012503:Saponins / Q000494:pharmacology*
D002147:Calmodulin; D012503:Saponins; D000246:Adenosine Diphosphate Ribose; D004533:Egtazic Acid; D002118:Calcium