With the emergence of transgenic animal models for human cardiac diseases, the mouse heart has moved into the focus of interest. However, little is known about cardiac region specific Ca2+ signalling in atrial and ventricular myocytes of wildtype mice. We investigated such differences by isolating ventricular, right and left atrial myocytes using retrograde enzyme perfusion and compared global Ca2+ signalling in Fura-2 loaded cells.

In electrically stimulated ventricular myocytes we found two groups with respect to post rest behaviour: the majority of cells displayed pronounced post rest potentiation whereas other types of behaviour also have been observed. Atrial myocytes from left and right atria exhibited different global Ca2+ signalling. When challenged with 10 mM caffeine to probe the SR- Ca2+ content we also identified differences between the myocytes depending on the cardiac origin.

From these results we conclude that many properties of Ca2+ signalling in mouse cardiac myocytes depend very much on the particular origin of the cell and that these properties have to be considered when working with wildtype and transgenic mice.