Localization of angiotensin AT1 receptors in the rat heart conduction system

We characterized angiotensin II receptor subtypes in the conduction system of the rat heart using quantitative autoradiography. In both the sinoatrial and atrioventricular nodes, binding could be totally displaced by losartan, and was insensitive to PD 123177, indicating that angiotensin II receptors in the conduction system of the rat heart belong to the AT1 subtype. Angiotensin AT1 receptors could play a direct role in the regulation of the heart chronotropic properties.