Cardiovascular and Respiratory Responses to Heme Oxygenase Inhibition in Conscious Rats
Many studies have indicated that endogenous carbon monoxide (CO) generated by the heme oxygenase (HO) system plays a physiological role as a second messenger (Maines, 1997). Although it has been suggested that the HO inhibitor-induced pressor response is mediated by the autonomic nervous system (Johnson et al. 1995), no direct evidence has been demonstrated by neural recordings. Furthermore, a recent study found that CO appears to modulate carotid body sensory activity (Prabhakar et al. 1995). However, the effect of HO inhibitor on tonic ventilatory regulation in conscious animals has not been examined. Accordingly, the main purpose of this study was to examine the respiratory response and the role of the autonomic nervous system in regulation of the cardiovascular response to the administration of zinc deuteroporphyrin 2, 4-bis glycol (ZnDPBG), an inhibitor of HO activity, in conscious rats. To assess the contribution of peripheral chemoreceptors (carotid and aortic bodies) to these responses, we also examined the effect of HO inhibition on respiration and the cardiovascular system in arterial chemo-denervated rats.
KeywordsHeme Oxygenase Mean Arterial Blood Pressure Carotid Body Respiratory Response Renal Sympathetic Nerve Activity
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