The specialised cardiac conduction system (CCS) is responsible for the generation and conduction of the action potential. It consists of the sinus node (SN), atrioventricular node (AVN), His bundle and Purkinje fibres. Further areas of specialised tissue – atrioventricular ring tissue (AVRT) also exists and it consists of rings of nodal-like myocytes around the tricuspid, mitral and aortic valves forming the left, right and aortic rings (LR, RR, AR), which unite to form the retroaortic node (RAN). Electrophysiologically, the AVRT is different, for example the action potential recorded from RR cells is shorter, maximum diastolic potential is more negative and pacemaker potential is less steep compared to SN cells (Rozanski & Jalife, 1986). The aim of this study was to investigate the expression of ion channels in the AVRT and compare their expression to that in the CCS and/or working myocardium to understand their unique electrophysiological properties. 12 hearts were obtained from 3 months old Wistar-Hannover rats (euthanized via cervical dislocation in accordance with the United Kingdom Animals Act, 1986); the hearts were retrieved, frozen and cryosectioned. Immunohistochemistry was used to label serial sections for HCN4 (marker of the CCS/AVRT) and Cx43 (marker of the working myocardium) to visualise the areas of interest. Laser assisted microdissection was used to collect AM (atrial muscle), VM (ventricular muscle), SN, AVN, RR and RAN from adjacent serial sections. qPCR was used to measure the level of mRNAs for nodal markers (ANP and Tbx3), Connexins (Cx40, Cx43, Cx45) and ion channels responsible for If (HCN1, HCN4), INa (Nav1.5), ICaL (Cav1.2, Cav1.3), ICaT (Cav3.1), Ito (Kv1.4, Kv4.2), IKur (Kv1.5), IKr (ERG), IKs (KvLQT1), IK1 (Kir2.1), and IKAch (Kir3.1) normalised to the house keeping gene 28S. One-way ANOVA was used to identify the significant difference (P<0.05). The results showed that ANP was less expressed in the VM (58±33), RR (453±167), RAN (529±256) and AVN (1406±832) compared to the AM (1941±626). Tbx3 was more expressed in the AVN (32±7) and SN (27±10) than in the RAN (11±3), RR (9±2), AM (3±2) and VM (2±1). Cx43 was more expressed in the VM (169±73) as compared to the SAN (22±13), RR (5±1), AVN (8±3) and RAN (9±4). HCN4 was more expressed in the AVN (443±146) than in the RAN (124±54), RR (76±24), AM (29±15), VM (23±8) and SN (242±45). Cav1.3 was more expressed in the AVN (44±18) than in the VM (5±2), AM (9±3), RR (11±2). Cav3.1 was more expressed in the AVN (115±39) than in the VM (9±1), AM (35±12), RR (28±12), RAN (41±15) and SN (50±15). Kir2.1 was more expressed in the VM (149±72) than in the RAN (11±3), RR (16±8), AVN (17±5), SN (13±5) and AM (31±12). In conclusion, our data show that the AVRT shows a unique profile in the expression of ion channels that may explain the unique electrophysiological properties of this specialised tissue.