| Contributors: Mike Berridge, Bill Catterall, Jim Stull, Shaun Coughlin, and Eric Olso |
| Artwork by: Gil R. Sambrano and Roger Sunahara |
| Contraction of cardiac cells is driven by Ca2+ that enters through channels in the membrane before being amplified by release of Ca2+ through ryanodine receptors (RYRs) on the internal storage organelles. These organelles also release smaller amounts of Ca2+ in response to receptor- mediated generation of inositol trisphosphate (IP3). In addition to controlling contraction, Ca2+ acts through calmodulin (CAM) to stimulate a variety of signaling pathways that have been implicated in the control of gene transcription and cardiac hypertrophy. Ca2+ signaling is modulated by G protein-coupled receptors operating through the cAMP/PKA (see the cAMP module) and the DAG/PKC messenger pathways. |