Abstract
Recent studies suggest that carbon monoxide (CO), which is produced in significant quantities in many brain regions, may function as a neurotransmitter. Heme oxygenase catalyzes the metabolism of heme to CO and biliverdin; however, the physiological role of CO in central cardiovascular regulation was not well understood. In the present study, we evaluated the baroreflex response of CO in the nucleus tractus solitarii (NTS) of rats. Male Sprague-Dawley rats were anesthetized with urethane, and blood pressure and heart rate were monitored intra-arterially. Unilateral microinjection (60 nL) of hematin, a heme molecule cleaved by heme oxygenase to yield CO, into the NTS produced prominent dose-related depressor and bradycardic effects. Baroreflex responses were elicited by increasing doses of phenylephrine (10 to 30 microg/kg IV) before and after intra-NTS administration of zinc deuteroporphyrin 2,4-bis-glycol (ZnDPBG) (1 nmol), an inhibitor of heme oxygenase activity, or vehicle alone. The reflex bradycardia elicited by phenylephrine was significantly inhibited by pretreatment with ZnDPBG. Furthermore, the inhibitory effect of ZnDPBG on baroreflex activation was dose dependent. These results suggest CO formed by brain heme oxygenase plays a significant role in central cardiovascular regulation and that inhibition of heme oxygenase attenuated baroreflex activation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
