Ca2+ transients in perfused hearts revealed by gated 19F NMR spectroscopy

E Marban, M Kitakaze, V P Chacko, M M Pike
1988 Circulation Research  
Gated acquisition of "T nuclear magnetic resonance spectra from perfused ferret hearts loaded with the fluorinated Ca I+ indicator 5,5'-F 2 -BAPTA allows direct quantitation of the cyclical changes in the intracellular free Ca 2+ concentration ([Ca 2+ ],) that underlie contraction in intact hearts. [Ca 2+ ], increased from approximately 200 nM in diastole to -1 fiM or higher hi early systole. Although the 19 F spectra that report [Ca 2+ ], changed dramatically and reproducibly during the
more » ... y during the cardiac cycle, no changes were detectable in gated phosphorus spectra. We exploited the ability to control the coronary arterial flow of our hearts to investigate the mechanism of the fall in contractility that results from a decrease in perfusion even when the flow suffices to sustain normal high energy phosphate concentrations. Under these conditions, the amplitude of Ca 2+ transients falls markedly along with the decline in pressure. This down-regulation of Ca 2+ transients constitutes a novel protective mechanism that minimizes energy demand during lowflow ischemia.
doi:10.1161/01.res.63.3.673 pmid:3136952 fatcat:sgdjxvi5wfgxvibqvgzp4wjoy4