These authors contributed equally to this work.
cAMP- and Ca2+/calmodulin-dependent protein kinases mediate inotropic, lusitropic and arrhythmogenic effects of urocortin 2 in mouse ventricular myocytes
Article first published online: 14 DEC 2010
© 2010 The Authors. British Journal of Pharmacology © 2010 The British Pharmacological Society
British Journal of Pharmacology
Volume 162, Issue 2, pages 544–556, January 2011
How to Cite
Yang, L.-Z., Kockskämper, J., Khan, S., Suarez, J., Walther, S., Doleschal, B., Unterer, G., Khafaga, M., Mächler, H., Heinzel, F. R., Dillmann, W. H., Pieske, B. and Spiess, J. (2011), cAMP- and Ca2+/calmodulin-dependent protein kinases mediate inotropic, lusitropic and arrhythmogenic effects of urocortin 2 in mouse ventricular myocytes. British Journal of Pharmacology, 162: 544–556. doi: 10.1111/j.1476-5381.2010.01067.x
- Issue published online: 14 DEC 2010
- Article first published online: 14 DEC 2010
- Accepted manuscript online: 13 OCT 2010 07:45AM EST
- Received; 18 March 2010; Revised; 11 August 2010; Accepted; 7 September 2010
- urocortin 2;
- ventricular myocyte;
- protein kinase A;
- Ca2+/calmodulin-dependent protein kinase II
BACKGROUND AND PURPOSE Urocortin 2 is beneficial in heart failure, but the underlying cellular mechanisms are not completely understood. Here we have characterized the functional effects of urocortin 2 on mouse cardiomyocytes and elucidated the underlying signalling pathways and mechanisms.
EXPERIMENTAL APPROACH Mouse ventricular myocytes were field-stimulated at 0.5 Hz at room temperature. Fractional shortening and [Ca2+]i transients were measured by an edge detection and epifluorescence system respectively. Western blots were carried out on myocyte extracts with antibodies against total phospholamban (PLN) and PLN phosphorylated at serine-16.
KEY RESULTS Urocortin 2 elicited time- and concentration-dependent positive inotropic and lusitropic effects (EC50: 19 nM) that were abolished by antisauvagine-30 (10 nM, n= 6), a specific antagonist of corticotrophin releasing factor (CRF) CRF2 receptors. Urocortin 2 (100 nM) increased the amplitude and decreased the time constant of decay of the underlying [Ca2+]i transients. Urocortin 2 also increased PLN phosphorylation at serine-16. H89 (2 µM) or KT5720 (1 µM), two inhibitors of protein kinase A (PKA), as well as KN93 (1 µM), an inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMKII), suppressed the urocortin 2 effects on shortening and [Ca2+]i transients. In addition, urocortin 2 also elicited arrhythmogenic events consisting of extra cell shortenings and extra [Ca2+]i increases in diastole. Urocortin 2-induced arrhythmogenic events were significantly reduced in cells pretreated with KT5720 or KN93.
CONCLUSIONS AND IMPLICATIONS Urocortin 2 enhanced contractility in mouse ventricular myocytes via activation of CRF2 receptors in a cAMP/PKA- and Ca2+/CaMKII-dependent manner. This enhancement was accompanied by Ca2+-dependent arrhythmogenic effects mediated by PKA and CaMKII.