An afferent explanation for sexual dimorphism in the aortic baroreflex of rat

dc.contributor.authorSanta Cruz Chavez, Grace C.
dc.contributor.authorLi, Bai-Yan
dc.contributor.authorGlazebrook, Patricia A.
dc.contributor.authorKunze, Diana L.
dc.contributor.authorSchild, John H.
dc.contributor.departmentDepartment of Biomedical Engineering, Purdue School of Engineering and Technology, IUPUIen_US
dc.date.accessioned2016-03-24T15:40:22Z
dc.date.available2016-03-24T15:40:22Z
dc.date.issued2014-09-15
dc.description.abstractSex differences in baroreflex (BRx) function are well documented. Hormones likely contribute to this dimorphism, but many functional aspects remain unresolved. Our lab has been investigating a subset of vagal sensory neurons that constitute nearly 50% of the total population of myelinated aortic baroreceptors (BR) in female rats but less than 2% in male rats. Termed “Ah,” this unique phenotype has many of the nonoverlapping electrophysiological properties and chemical sensitivities of both myelinated A-type and unmyelinated C-type BR afferents. In this study, we utilize three distinct experimental protocols to determine if Ah-type barosensory afferents underlie, at least in part, the sex-related differences in BRx function. Electron microscopy of the aortic depressor nerve (ADN) revealed that female rats have less myelin (P < 0.03) and a smaller fiber cross-sectional area (P < 0.05) per BR fiber than male rats. Electrical stimulation of the ADN evoked compound action potentials and nerve conduction profiles that were markedly different (P < 0.01, n = 7 females and n = 9 males). Selective activation of ADN myelinated fibers evoked a BRx-mediated depressor response that was 3–7 times greater in female (n = 16) than in male (n = 17) rats. Interestingly, the most striking hemodynamic difference was functionally dependent upon the rate of myelinated barosensory fiber activation. Only 5–10 Hz of stimulation evoked a rapid, 20- to 30-mmHg reduction in arterial pressure of female rats, whereas rates of 50 Hz or higher were required to elicit a comparable depressor response from male rats. Collectively, our experimental results are suggestive of an alternative myelinated baroreceptor afferent pathway in females that may account for, at least in part, the noted sex-related differences in autonomic control of cardiovascular function.en_US
dc.identifier.citationSanta Cruz Chavez, G. C., Li, B.-Y., Glazebrook, P. A., Kunze, D. L., & Schild, J. H. (2014). An afferent explanation for sexual dimorphism in the aortic baroreflex of rat. American Journal of Physiology - Heart and Circulatory Physiology, 307(6), H910–H921. http://doi.org/10.1152/ajpheart.00332.2014en_US
dc.identifier.urihttps://hdl.handle.net/1805/9017
dc.language.isoen_USen_US
dc.publisherAmerican Physiological Society (APS)en_US
dc.relation.isversionof10.1152/ajpheart.00332.2014en_US
dc.relation.journalAmerican Journal of Physiology - Heart and Circulatory Physiologyen_US
dc.rightsPublisher Policyen_US
dc.sourcePMCen_US
dc.subjectbaroreceptoren_US
dc.subjectcardiovascularen_US
dc.subjectvagalen_US
dc.subjectautonomic nervous systemen_US
dc.subjectvisceralen_US
dc.titleAn afferent explanation for sexual dimorphism in the aortic baroreflex of raten_US
dc.typeArticleen_US
ul.alternative.fulltexthttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC4166749/en_US
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