The application of capsaicin to the epicardium of the left ventricle consistently results in increases in blood pressure and heart rate.22 Studies have shown that there are pressor and depressor responses to topical or intracoronary administration of these chemical agents. Felder and Thames16 reported that topical application of bradykinin elicited inhibitory, excitatory, and biphasic responses. Excitatory and inhibitory reflexes were eliminated by cardiac sympathetic afferent denervation. Injection of capsaicin into the left circumflex coronary artery caused systemic hypotension and bradycardia, a pressor response associated with tachycardia, or a biphasic effect. The reflex hypotension and bradycardia were reversed to increases in blood pressure and heart rate after bilateral vagotomy.17 Our results support these findings, with the exception that changes in heart rate were minimal, probably as a result of the barbiturate anesthesia. Anesthesia in general can inhibit reflex responses, and barbiturates have been known to attenuate neurally mediated changes in blood pressure and heart rate. Although the changes in heart rate and blood pressure that we report are relatively small, they are qualitatively comparable to what others have reported.16,22 In some cardiac reflex studies, α-chloralose, which may accentuate certain reflexes, has been used.17,23 With chloralose, however, the level of anesthesia may be light, making it necessary to use other anesthetics and drugs for muscular relaxation. Thus, there may be additional confounding variables. In a pilot study, we used isoflurane, but were not able to evoke cardiac chemoreflexes consistently. However, with a continuous infusion of pentobarbital, animals were well anesthetized, and the reflex changes in blood pressure and dP/dt were consistent; only the heart rate responses were variable. This could result from anesthesia, or perhaps from competing reflex responses.