Abstract
The current study investigated cardiovascular function and the baroreflex using male Sprague Dawley rats as a model. The 36 male rats used in this study were surgically prepared for femoral artery and vein cannulation in order to measure blood pressure and allow for IV injections, respectively. Each rat had a tracheostomy procedure in order to keep the airway clear of mucus and debris. In addition, both vagus nerves were isolated and prepared for a bilateral vagotomy. Phenylephrine (PE) and sodium nitroprusside (SNP) were administered to these rats by IV injection to cause an increase and a decrease in blood pressure, respectively, first with both vagus nerves intact, and then after a bilateral vagotomy. The hypothesis for this investigation was that the bilateral vagotomy would cause a greater than normal increase in blood pressure and heart rate in response to PE administration but no such change in blood pressure and heart rate in response to SNP administration. It was found that the percent changes from baseline to peak drug effect mean arterial pressure (MAP) values showed significant differences (p < 0.05) between the respective pre-vagotomy and post-vagotomy groups regarding both PE and SNP administration. No such statistical differences were found for the percent change data regarding heart rate. Therefore, this study demonstrated that the body retains the ability to regulate blood pressure when the baroreflex is inhibited by a bilateral vagotomy. Physiological control mechanisms, such as atrial natriuretic peptide (ANP), renin-aldosterone system, and the Bezold-Jarisch reflex, may account for the body’s ability to return blood pressure back to its normal range after various perturbations. Further studies are necessary to investigate the impact these mechanisms may have on the current results as well as the physiology of vasovagal syncope.
Year
2022
Document Type
Thesis
Keywords
Cardiovascular Physiology, Baroreceptor Reflex, Bilateral Vagotomy, Phenylephrine, Sodium Nitroprusside
Degree Name
Master of Science (MS)
Department
Animal Physiology
Advisor
Dr. Inefta Reid
Recommended Citation
Branigan, Philip J., "An In-Vivo Investigation of Cardiovascular Function and the Baroreflex" (2022). Electronic Dissertations and Theses, 2010-current. 174.
https://commons.library.stonybrook.edu/electronic-disserations-theses/174