Myocardial ischemia causes release of metabolites such as bradykinin, which stimulates cardiac sensory receptors to evoke a sympathoexcitatory reflex. However, the phenotype of afferent neurons and fibers mediating this reflex response is not clear. In this study, we tested the hypothesis that the cardiogenic sympathoexcitatory reflex is mediated by capsaicin-sensitive afferent fibers. Enhanced immunoflorescence labeling revealed that VR1-containing afferent nerve fibers were present on the epicardial surface of the rat heart. Resiniferatoxin (RTX), a potent analog of capsaicin, was used to deplete capsaicin-sensitive afferent fibers in rats. Depletion of these fibers was confirmed by substantial reduction of VR1 immunoreactivity in the epicardium and dorsal root ganglia. The thermal sensitivity was also diminished in RTX-treated rats. Renal sympathetic nerve activity (RSNA) and blood pressure were recorded in anesthetized rats during epicardial application of bradykinin or capsaicin. In vehicle-treated rats, epicardial bradykinin (10 g/ml) or capsaicin (10 g/ml) application produced a significant increase in RSNA and arterial blood pressure. The RSNA and blood pressure responses caused by bradykinin and capsaicin were completely abolished in RTX-treated rats. Furthermore, epicardial application of iodo-RTX, a highly specific antagonist of VR1 receptors, blocked capsaicin- but not bradykinin-induced sympathoexcitatory responses. Thus, these data provide important new information that the heart is innervated by VR1-expressing afferent nerves and these afferent nerves are essential for the cardiogenic sympathoexcitatory reflex during myocardial ischemia.