Ryanodine receptor (RyR2) is an intracellular calcium channel located on the sarcoplasmic reticulum (SR) membrane through which calcium flows during the process known as Calcium Induced Calcium Release (CICR) (Fabiato and Fabiato, 1978). There are three phosphorylation sites of RyR2, RyR2 phospho-Ser2808 which is phosphorylated by protein kinase A (PKA) and calcium/CaM Kinase II, RyR2 phospho-Ser2814 which is phosphorylated by CaM Kinase II and RyR2 phospho-Ser2030 which is phosphorylated by PKA. However, abnormalities in RyR2 function may contribute to the pathophysiology of various cardiac diseases. The aim of this study is to investigate, using Western Blotting, whether there are any significant differences in RyR2 and its phosphorylated subunits in each of the cardiac chambers of Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHRs) as well as from tissues derived from a volume-overload. Total RyR2 showed no significant differences between any of the different heart chambers of WKY and SHR or shunt and sham-operated tissues. In terms of RYR2 phospho-Ser2808 there was an increase in this phosphorylation state of the RyR in left and right ventricular homogenates of the WKY compared to SHR. This pattern was also observed in sham-operated homogenates compared to their shunt-operated counterparts. The difficulty of detecting the phosphorylation of RyR2 at Ser-2814 and Ser-2030 compared to Ser-2808 is due to RyR2 being mainly phosphorylated by PKA with only a small contribution from CAM kinase II (Huke and Bers, 2008). We managed to obtain signals however for shunt and sham atrial and ventricular homogenates (though there were no significant differences between the healthy and disease states) even though there were no detectable signals for WKY homogenates for RyR2 phospho-Ser2814. This may be due to species differences amongst the rats (sham homogenates originated from Sprague-Dawley (SD) normotensive rats). SD rats have similar blood pressure to SHR rats but not WKY rats however WKY rats are genetically more similar to the SHR rats (Mills and Bruckert, 1988), hence these may account for the variable detection of these proteins expressed in different cardiac tissues.