Loyola University Chicago Loyola eCommons Dissertations Theses and Dissertations 1976 Interaction of Descending Sympathetic Pathways and Afferent Nerves in Cardiovascular Regulation Susan Marie Barman Loyola University Chicago Follow this and additional works at: https://ecommons.luc.edu/luc_diss Part of the Medicine and Health Sciences Commons Recommended Citation Barman, Susan Marie, "Interaction of Descending Sympathetic Pathways and Afferent Nerves in Cardiovascular Regulation" (1976). Dissertations. 1571. https://ecommons.luc.edu/luc_diss/1571 This Dissertation is brought to you for free and open access by the Theses and Dissertations at Loyola eCommons. It has been accepted for inclusion in Dissertations by an authorized administrator of Loyola eCommons. For more information, please contact [email protected]. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License. Copyright © 1976 Susan Marie Barman INTERACTION OF DESCENDING SYMPATHETIC PATHWAYS AND AFFERENT NERVES IN CARDIOVASCULAR REGULATION by Susan Marie Barman A Dissertation Submitted to the ·Faculty of the Graduate School of Loyola University of Chicago in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy February 1976 UBTI/'1l1Y LOYOLl•. U\rrv:,--; '""Y i' 'rn;r '\ T. CFl\i'TFR DEDICATION I dedicate this work to my late Mother, whose hopeful expections have been realized. ii BIOGRAPHY Susan Marie Barman was born in Joliet, Illinois, on August 28, 1949. She attended parochial grade schools and graduated from St. Francis Academy, Joliet, in 1967. Susan attended Loyola University, Chicago, Illinois, from 1967 - 1971. During her Senior year, she was a la­ boratory assistant in Human Anatomy and Physiology, under the direction of Drs. M. Goldie and E. Cardona. She grad­ uated with a Bachelors of Science Degree in Biology in \June, 1971. Susan entered graduate school in August, 1971, in the Department of Physiology at Indiana University Medical Center, Indianapolis, Indiana. In June, 1972, she trans­ ferred to Loyola University, Department of Physiology, Maywood, Illinois. In September, 1972, she began to study under the direction of Dr. Robert D. Wurster, and was sup­ ported by a Research Training Grant qf the National Insti­ tute of General Medical Sciences of the National Institute of Health. iii - BIOGRAPHY (continued} Susan has accepted a two-year Research Associate position with Dr. Gerard L. Gebber, Professor of Pharma­ cology, Michigan State University, East Lansing, Michigan. Susan is a student member of the Society of Neuro­ science and an associate member of the American Physio­ logical Society and Sigma Xi. She is also a member of the National Jesuit Honor Society. iv ACKNOWLEDGMENT At this time. I would like to extend my sincere ap­ preciation to my advisor, Dr. Robert D. Wurster. Through­ out the past three years he has challenged me to develop patience and perserverance during a scientific investiga­ tion and, thereby, to mature as an independent researcher. Dr. Walter C. Randall, who served as Chairman of the Department of Physiology during the major part of this investigation, will long be remembered and admired for \striving to maintain a Department with free communication between faculty and students. I am extremely grateful to Dr. Robert D. Foreman who was instrumental in developing my interest in the spinal cord control of the sympathetic nervous system. His spirit of friendship and encouragement have helped me through many of the rough moments experienced in attaining this degree. The use of the PDP-12 Computer would have been im­ possible without the long hours of work by Dr. Thomas V. v ACKNOWLEDGMENT (continued) Mccaffrey. His time and effort in modifying programs to suit the needs of this investigation and in training me in the operation of these programs were invaluable aids to this research. I would also like to thank Mr. Jin Mo Chung and the many other students who have shared their time with me in discussing my research and offering suggestions. / In addition, their friendships will long be remembered and cherished. My sincere appreciation is extended to Ms. Helena Mauceri. The many hours she spent in helping me with the figures in this dissertation, and most especially her un~ compromising friendship, will never be forgotten. I am also grateful to Ms. Carol Birk for her long hours of patient work while typing this dissertation. vi -- TABLE OF CONTENTS Chapter Page I. INTRODUCTION AND STATEMENT OF PURPOSE .............. l II. LITERATURE REVIEW A. Cerebral Cortex and Limbic System ............. 4 B. Hypothalamus . ................... .- ............ 12 C. Mesencephalon ................................ 28 D. Medulla ...................................... 33 E. Spinal Cord .................................. 56 F. Afferent Nerves .................. ~···········74 III. MATERIALS AND METHODS A. General Animal Preparation .....•.........•... 92 B. Spinal Cord Preparation ...................... 93 C. Afferent Nerve Preparation ................... 93 D. T2 Preganglionic Nerve Preparation ........... 94 E. Stimulation Techniques •.............•........ 94 F. Recording Techniques ......................... 9 6 G. · Experimental Protocols .....................•. 9 8 H. Statistical Analysis ........................ 109 IV. RESULTS AND DISCUSSION A. Cardiovascular and Electrophysiological Responses to Variations in Stimulus Parameters of Descending Sympatho- Excitatory Pathways ......................... 110 B. Cardiovascular arid Electrophysiological Responses to Stimulation of Descending Spinal Sympatho-Inhibitory Pathways ......... 128 C. Cardiovascular and Electrophysiological Responses to Afferent Nerve Stimulation ..... 145 D. Interaction of Descending Sympatho­ Excitatory and Sympatho-Inhibitory Pathways .. ................................. 155 vii TABLE OF CONTENTS (continued) Chapter Page IV. RESULTS AND DICSUSSION (continued) E. Baroreceptor Interaction with Descending Spinal Sympatho­ Excitatory Pathways and Afferent Nerves ...................................... 184 F. Interaction of Descending Sympatho­ Excitatory Pathways and Afferent Nerves ...................................... 203 G. Interaction of Descending Sympatho­ Inhibitory Pathways and Afferent Nerves .•........•. ·•....................•.... 222 .V. GENERAL DISCUSSION ............................... 245 VI. CONCLUSIONS ........... ~ .......................••. 256 BIBLIOGRA.PHY . .....•.•.•..........••••.•..•.....••....•... 2 6 2 viii - LIST OF FIGURES Figure Page 1. DIAGRAM OF INSTRUMENTS .........•.....•.•.•••...•.. 9 5 2. STIMULATION OF DESCENDING SYMPATHO- EXCITATORY PATHWAYS ..•...........••..........•... 112 3. RELATIONSHIP BETWEEN BLOOD PRESSURE AND SYMPATHETIC NERVE ACTIVITY ......•......•.••.. 115 4. STIMULATION OF DESCENDING SYMPATHO- INHIBITORY PATHWAYS ...•.•..•.••.................. 130 5. DEPRESSOR RESPONSES AT VARIOUS STIMULUS FREQUENCIES ....•.........•.......••.•.•. 132 1 6. T2 PREGANGLIONIC NERVE RESPONSES TO SYMPATHO-INHIBITORY STIMULATION .................. 139 7. STIMULATION OF AFFERENT NERVE FIBERS ...•...•..•.. 146 8. SOMATO-SYMPATHETIC REFLEXES ...•..............•... 152 9. INTERACTION OF EXCITATORY AND INHIBITORY PATHWAYS ...•....•..................... 156 10. EFFECTS OF EXCITATORY STIMULATION ON DEPRESSOR RESPONSES ...................•.•..... 160 11. EFFECTS OF VASOMOTOR TONE ON DEPRESSOR RESPONSES .. •.•.•.....•.....•.....•..•...••.•..•... 16 3 12. EFFECTS OF INHIBITORY STIMULATION ON PRESSOR RESPONSES ......•....•........•...•.....•. 166 ix --- LIST OF FIGURES (continued) Figure Page 13. SIMULTANEOUS STIMULATION OF EXCITATORY AND INHIBITORY PATHWAYS •....................•.... 169 14. INTERACTION OF EXCITATORY AND INHIBITORY PATHWAYS .......•..•..........••....•.• 174 15. INHIBITION OF EVOKED DISCHARGES IN T2 PREGANGLIONIC ~ERVE ..•...•..•.....•..........• 177 16. EVOKED DISCHARGES DURING BARORECEPTOR ACTIVATION .....•.•..•.................•....•....•. 185 17. BARORECEPTOR-INDUCED SYMPATHO- INHIBITION·· •...•.•.••.....•..•......•...•..•.•.... 18 8 18. SO.MATO-SYMPATHETIC REFLEXES DURING BARORECEPTOR ACTIVATION .•...••..•••...•••••.•••.• 190 19. BARORECEPTOR-INDUCED INHIBITION OF SOMATO-SYMPATHETIC REFLEXES ...•..•......••......• 193 20. PREGANGLIONIC NERVE DISCHARGES DURING CAROTID OCCLUSION •.....•...•........•.•...•...... 196 21. INTERACTION OF EXCITATORY PATHWAYS AND AFFERENT NERVES ...•....•.••.....•....•....... 2 0 5 22. FACILITATION OF SOMATO-SYMPATHETIC REFLEXES . .•••.•................•...•............. 210 23. FACILITATION OF LATE REFLEX ............•..••....• 214 x LIST OF FIGURES (continued) Figure Page 24. EFFECTS OF AFFERENT STIMULATION ON DEPRESSOR RESPONSES •••••••••••.•••.••••••...•• 224 -25. EFFECTS OF INHIBITORY STIMULATION ON PRES SOR RESPONSES •••.••••••••••••••••.••••.•.• 2 2 7 26. SIMULTANEOUS STIMULATION OF INHIBITORY PATHWAYS .A.ND AFFERENT NERVES • •••••••••••••••••••••••••••••••••••••••••• 2 31 27. EFFECTS OF INHIBITORY STIMULATION ON REFLEX DISCHARGES •.••.•.•••.•••••••..•..•.••.• 2 35 xi - CHAPTER I INTRODUCTION AND STATEMENT OF PURPOSE Neural regulation of the cardiovascular system in- volves the integrative action of every level of the nerv- ous system. However, the medulla has long been recognized as the site of the major "vasomotor center." Classical experiments from Ludwig's laboratory, demonstrating the important role of the medulla in both tonic and ref lex control of the circulation, have_. been repeatedly veri­ fied (7, 138, 142, 188).