Ca2+ sparks and Ca2+ waves in saponin‐permeabilized rat ventricular myocytes
- 1 December 1999
- journal article
- Published by Wiley in The Journal of Physiology
- Vol. 521 (3) , 575-585
- https://doi.org/10.1111/j.1469-7793.1999.00575.x
Abstract
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).Keywords
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