High resolution

Module 6: Figure cyclic AMP microdomains

Visualization of cyclic AMP microdomains in cardiac myocytes.

A fluorescence resonance energy transfer (FRET)-based protein kinase A (PKA) sensor was used to detect cyclic AMP microdomains in a cardiac myocyte. (a) The fluorescence produced by the FRET partners, which where the catalytic and regulatory subunits of PKA, formed striations along the Z line. (b) Addition of noradrenaline (Ne) caused an increase in fluorescence, indicating the formation of cyclic AMP, which was increased further upon addition of the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX). (c) The boxed region in panel a was imaged at 60 s (i.e. at the peak of the Ne response), revealing that the increase in cyclic AMP was localized to the Z lines. (d) When imaged at 200 s (i.e. after the addition of IBMX), there was a large increase in fluorescence that was now more spread out. Reproduced from Curr. Opin. Cell Biol., Vol. 14, Zaccolo, M., Magalhães, P. and Pozzan, T., Compartmentalisation of cAMP and Ca2+ signals, pp. 160–166. Copyright (2002), with permission from Elsevier; see Zaccolo et al. 2002.