Lay summary
In the present research project Ca2+ signaling is investigated in cardiac muscle cells on the cellular and subcellular level using a combination of biophysical and molecular biology methods (laser-scanning confocal microscopy, UV-laser flash photolysis of caged compounds, two-photon excitation of fluorescent indicators and caged compounds, the patch-clamp technique, expression of cloned genes and antisense inhibition of expression). In particular, properties of the recently discovered elementary events of cellular Ca2+ signaling, the Ca2+ sparks, are examined. In addition, the role of the Na-Ca exchanger and several ion channels is analyzed in the process of Ca2+ signaling and cardiac contraction. In heart muscle cells the L-type Ca channels (DHP receptors), the SR Ca2+ release channels (Ryanodine receptors) and the Na-Ca exchangers are important regulators of the Ca2+-homeostasis and thus determine the force produced during each heart-beat.