ATTENUATION OF RAPID ONSET VASODILATION WITH ADVANCED AGE: ROLES OF ADRENERGIC AND ENDOTHELIAL SIGNALING _______________________________________ A Dissertation presented to the Faculty of the Graduate School at the University of Missouri-Columbia _______________________________________________________ In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy _____________________________________________________ by SHENGHUA YUAN SINKLER Dr. Steven S. Segal, Dissertation Supervisor MAY 2016 The undersigned, appointed by the dean of the Graduate School, have examined the dissertation entitled ATTENUATION OF RAPID ONSET VASODILATION WITH ADVANCED AGE: ROLES OF ADRENERGIC AND ENDOTHELIAL SIGNALING presented by Shenghua Sinkler, a candidate for the degree of doctor of philosophy, and hereby certify that, in their opinion, it is worthy of acceptance. Professor Steven S. Segal Professor Cheryl M. Heesch Professor Paul Fadel Professor Michael Hill Professor Virginia Huxley ACKNOWLEDGEMENTS I would like to acknowledge and thank my dissertation supervisor, Prof. Steven S. Segal, who dedicates a substantial amount of time into my research project and development of my academic skills in writing and presentation, and is always there with great patience to provide his support and walk me through the process of learning. I would like to thank Dr Erika Boerman for teaching me immunostaining and analyzing the perivascular innervations, and for her insightful comments and encouragement for my publications and grant application. I also would like to thank other members of the Segal lab for making the lab a friendly and fun place to work. ii TABLE OF CONTENTS ACKNOWLEDGEMENTS ................................................................................................ ii LIST OF FIGURES ........................................................................................................... vi LIST OF TABLES ........................................................................................................... viii LIST OF ABBREVIATIONS ............................................................................................ ix ABSTRACT ....................................................................................................................... xi CHAPTER 1. INTRODUCTION ....................................................................................................1 a. Functional Hyperemia ..................................................................................1 b. Vasodilation in Resistance Networks during Functional Hyperemia ..........2 c. Vascular Reactivity ......................................................................................3 d. Rapid Onset Vasodilation ............................................................................4 e. Aging Attenuates Muscle Blood Flow and ROV ........................................5 f. Functional Sympatholysis and Sympathetic Nerve Activity .......................6 g. Adrenergic Vasoconstriction and Aging ......................................................7 h. Endothelium Dependent Dilation and Aging ...............................................9 i. Ascending Vasodilation .............................................................................10 j. Gaps Exist in Current Understandings .......................................................11 k. General Methods ........................................................................................13 l. Purpose of Dissertation Research ..............................................................14 m. Peer reviewed Publications ........................................................................15 iii 2. AGING ALTERS REACTIVITY OF MICROVASCULAR RESISTANCE NETWORKS IN MOUSE GLUTEUS MAXIMUS MUSCLE .........................17 a. Abstract ......................................................................................................17 b. Introduction ................................................................................................18 c. Methods......................................................................................................20 d. Results ........................................................................................................25 e. Discussion ..................................................................................................28 f. Summary and Perspective ..........................................................................34 g. Acknowledgements ....................................................................................36 h. Author Contributions .................................................................................36 3. DIFFERENTIAL ADRENERGIC MODULATION OF RAPID ONSET VASODILATATION ALONG RESISTANCE NETWORKS OF SKELETAL MUSCLE IN OLD VERSUS YOUNG MICE ..................................................47 a. Key points ..................................................................................................47 b. Abstract ......................................................................................................48 c. Introduction ................................................................................................49 d. Methods......................................................................................................51 e. Results ........................................................................................................57 f. Discussion ..................................................................................................61 g. Summary and Perspective ..........................................................................69 h. Competing Interests ...................................................................................69 i. Author Contributions .................................................................................69 j. Funding Sources.........................................................................................69 k. Acknowledgements ....................................................................................69 iv 4. ROLE OF ENDOTHELIUM IN CONDUCTION AND INITIATION OF RAPID ONSET VASODILATION IN MOUSE SKELETAL MUSCLE .....................83 a. Abstract ......................................................................................................83 b. Introduction ................................................................................................84 c. Methods......................................................................................................86 d. Results ........................................................................................................92 e. Discussion ..................................................................................................96 f. Summary and Perspective ........................................................................104 5. CONCLUSIONS ..................................................................................................120 a. Summary ..................................................................................................120 b. Integration of Findings .............................................................................123 c. Implication of Current Findings...............................................................126 d. Future Directions .....................................................................................127 e. Final Comments ......................................................................................128 REFERENCES ................................................................................................................131 VITA ................................................................................................................................145 v LIST OF FIGURES Figure Page 1. Figure 2.1. ................................................................................................................37 2. Figure 2.2 .................................................................................................................39 3. Figure 2.3 .................................................................................................................40 4. Figure 2.4 .................................................................................................................42 5. Figure 2.5 .................................................................................................................43 6. Figure 2.6 .................................................................................................................44 7. Figure 2.7 .................................................................................................................45 8. Figure 2.8 .................................................................................................................46 9. Figure 3.1 .................................................................................................................73 10. Figure 3.2 .................................................................................................................74 11. Figure 3.3 .................................................................................................................75 12. Figure 3.4 .................................................................................................................76 13. Figure 3.5 .................................................................................................................77