Discrete Microdomains with High Concentration of cAMP in Stimulated Rat Neonatal Cardiac Myocytes

The second messenger cyclic adenosine monophosphate (cAMP) is the most important modulator of sympathetic control over cardiac contractility. In cardiac myocytes and many other cell types, however, cAMP transduces the signal generated upon stimulation of various receptors and activates different cellular functions, raising the issue of how specificity can be achieved. In the general field of signal transduction, the view is emerging that specificity is guaranteed by tight localization of signaling events. Here, we show that in neonatal rat cardiac myocytes, beta-adrenergic stimulation generates multiple microdomains with increased concentration of cAMP in correspondence with the region of the transverse…