This application describes a research plan and course of study leading to the Ph.D. degree as part of the M.D./Ph.D. Program at The University of Nebraska Medical Center. The overarching hypothesis of the research plan is that activation of central Rho-kinase by Angiotensin II (Ang II) contributes to sympathoexcitation in disease states (like heart failure, hypertension) and that Rho-kinase inhibition may be a therapeutic target in these diseases. To address this issue, three specific aims are proposed.
Specific Aim 1 : Determine the effect of central Rho-kinase inhibition on the regulation of autonomic tone in response to chronic systemic Ang II infusion. These experiments will be carried out in chronically instrumented, conscious New Zealand White rabbits. The Rho-kinase inhibitor, fasudil, will be administered intracerebroventricularly during Ang II infusion, and autonomic tone will be assessed in fasudil- and vehicle-treated rabbits by renal sympathetic nerve activity, baroreflex sensitivity, heart rate variability, changes in heart rate after metoprolol and atropine plasma norepinephrine, and changes in arterial pressure in response to ganglionic blockade.
Specific Aim 2 : Determine the effects of central Rho-kinase inhibition on the balance between sympatho-excitatory reactive oxygen species (ROS) and sympatho-inhibitory nitric oxide (NO) in sympathetic nuclei in response to systemic Ang II infusion. We will use several methods to quantify oxidative stress and a variety of proteins relevant to ROS and NO bioavailability in autonomic centers of the brainstem and hypothalamus. These studies will be performed on tissue from the rabbits used in Specific Aim 1.
Specific Aim 3 : Determine if overexpression of RhoA in vitro potentiates Ang II-mediated increases in ROS and decreases in NO bioavailability. In a neuronal cell line, we will evaluate the effects of overexpression of RhoA, the activator of Rho-kinase, on the balance between ROS and NO in response to Ang II stimulation, using the same molecular endpoints as Specific Aim 2. Overall, these studies will provide novel information on a neuronal pathway that could be a therapeutic target in sympathoexcitatory disease states. The didactic component of my training is also described, including journal club, seminar presentations, and courses in advanced physiology, statistics, engineering, and scientific writing. My comprehensive exam will be scheduled for late 2013 or early 2014. I will be supported to attend scientific conferences to present the results of my research. During my Ph.D. training, I will continue to be exposed to clinical medicine by assisting at a free clinic, shadowing UNMC physicians, and attending clinical seminars.
Research and a program of study are described for the Ph.D. component of the M.D./Ph.D. program at the University of Nebraska Medical Center. Mr. Pellegrino will carry out laboratory experiments designed to understand the role of Rho-kinase and RhoA in regulating sympathetic nerve activity in response to chronic Angiotensin II infusion. Didactic training will include advanced courses, workshops, seminars, and journal clubs. A thesis defense is planned for 2017.