Hormonal Regulation of Fluid and Electrolytes. Environmental Effects

Hormonal Regulation of Fluid and Electrolytes Environmental Effects

Hormonal Regulation of Fluid and Electrolytes Environmental Effects Edited by John R. Claybaugh TripIer Army Medical Center, Hawaii and Charles E. Wade Letterman Army Institute of Research San Francisco, California Plenum Press New York and London

Llbrarv of Congress Cataloging-In-Publication Data Hormonal regulation of fluid and electrolytes: environmental effects I edited by John R. Claybaugh and Charles E. Wade. p. cm. "ProceedIngs of a FederatIon of AmerIcan SocIetIes for ExperImental BIology Conference on Hormonal RegulatIon of FluId and Electrolytes: Envlron.ental Effects, held Aprl1 1-3, 1987, In WashIngton, O.C."--T.p. verso. Includes b1bllograph1cal references. ISBN-13: 978-1-4612-7878-8 e-isbn-13: 978-1-4613-0585-9 001: 10.1007/978-1-4613-0585-9 1. Water-electrolyte balance (Physlologyl--Endocr1ne aspects -Congresses. 2. Water-electrolyte balance (Phys1ologyl- -Env1ronmental aspects--congresses. 3. Hormones--Physlologlcal effect--congresses. I. Claybaugh, John R. II. Wade, Charles E. III. Federation of AmerIcan Soc1etles for Exper1mental BIology. IV. FederatIon of AmerIcan SocIeties for Exper1mental BIology Conference on Hormonal RegulatIon of FluId and Electrolytes: Environmental Effects (1987 : WashIngton, D.C.1 QP90.4.H67 1989 BI2'.01522--dc20 89-77900 CIP Proceedings of a Federation of American Societies of Experimental Biology Conference on Hormonal Regulation of Fluid and Electrolytes: Environmental Effects, held April 1-3, 1987, in Washington, D.C. 1989 Plenum Press, New York Softcover reprint of the hardcover 1st edition 1989 A Divisi<;>n of Plenum Publishing Corporation 233 Spring Street, New York, N.Y. 10013 All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or ot4erwise, without written permission from the Publisher

PREFACE The concept of this book has developed over the past fi fteen years as interest in the water and electrolyte disturbances associated with most environmental settings moved from a research area of descriptive discovery to one dealing with the mechanisms responsible for the previously observed disturbances. Most of the contributing authors have been involved in both aspects of this evolution of research, focusing on those problems associated with body fluid and electrolyte balance and searching for hormonal explanations. What did not accompany this transition, however, was a source of information encompassing the area of interest. Instead, the previous format of environmentally focused symposia, reviews, and books continued to be the only sources available. For instance, various books deal with the physiology of high altitude, space, or exercise but do not necessarily provide adequate coverage of water and electrolyte disturbances. To our knowledge, the format of this book is unique. We have made the central focus water and electrolyte physiology with an emphasis on endocrinology and tried to comprehensively cover this area of physiology in some of the more heavily studied environments. This book too, then, will have its limitations in coverage. For instance, in-depth coverage of the respiratory and cardiovascular responses to the high altitude en vironment will not be found, but since these areas are so integrally associated with water and electrolyte regulation they are not ignored. In addition to a reference text, hopefully this book will be used for some advanced graduate courses in environmental physiology, providing a starting point for future work. The editors would appreciate any comments on the utility of this book either as a reference or as a course text. The editors are indebted to Dr. Linda Kullama whose scientific knowledge of the field and editorial knowledge were invaluable assets in the completion of the final draft of this book. We would also like to take this opportunity to acknowledge and thank our editor at Plenum Publishing Corporation, Patricia Vann, for her encouragement, advice, patience, and sense of humor in completing this project. John R. Claybaugh Charles E. Wade v

CONTENTS Chapter 1 FLUID AND ELECTROLYTE HOMEOSTASIS DURING AND FOLLOWING EXERCISE: HORMONAL AND NON-HORMONAL FACTORS C.E. Wade, B.l. Freund, and J.R. Claybaugh Introd uction........... Non-Hormonal Effects of Exercise. Water and Electrolyte Balance during Exercise Thirst and Fluid Intake........... Renal Responses to Exercise......... Summary of Fluid and Electrolyte Homeostasis During Exercise Hormonal Effects of Exercise. Vasopressin....... Atrial Natriuretic Peptide. Renin-Angiotensin System. Aldosterone....... Other Hormones..... Factors Modulating Hormonal Responses to Exercise Summary. Conclusion. References. 1 1 1 4 6 12 13 13 18 22 27 30 31 33 33 34 Chapter 2 HORMONAL REGULATION OF FLUID AND ELECTROLYTES: EFFECTS OF HEAT EXPOSURE AND EXERCISE IN THE HEAT R.P. Francesconi, M.N. Sawka, R.W. Hubbard and K.B. Pandolf Introduction........................ 45 vii

Effects of Exogenous Hormones Sedentary Heat Exposure Exercise in the Heat Hypohydration Electrolytes Heat Acclimation. Plasma Volume. Future Studies Conclusion. References. 45 48 51 55 60 63 65 67 68 76 Chapter 3 EFFECT OF EXPOSURE TO COLD ON FLUID AND ELECTROLYTE EXCHANGE M.J. Fregly Introduction Effects of Exposure to Cold on Water Intake Effects of Acute Exposure to Cold in Rats Duration of Exposure to Cold Required to Induce Thermogenic Drinking in Rats.............. Effects of Food Intake on Water Intake in the Cold...... 87 87 87 88 89 Effects of Cold on Urine Production: Role of Antidiuretic Hormone........ 91 Mechanism of Thermogenic Drinking 93 Role of the Renin-Angiotensin System in Thermogenic Drinking. 94 Effect of a Ten-Day Cold Exposure on Electrolyte Exchange 95 Effect of Dietary Bulk on Water and Electrolyte Exchange in the Cold 103 Fluid Exchange During Four Weeks of Exposure to Cold. 108 Water Balance in Man Exposed to Cold. 111 Comments.... 112 viii

References.............................. 114 Chapter 4 HORMONAL AND RENAL RESPONSES TO HYPERBARIA S.K. Hong and J.R. Claybaugh Introduction........ Urinary Responses to Hyperbaric Exposure Body Fluid Balance During Hyperbaric Exposure Endocrine Responses...... Antidiuretic Hormone (ADH) Renin-Aldosterone... Prolactin.... Prostaglandin E2 (PGE 2 ) Parathyroid Hormone (PTH) Atrial Natriuretic Factor (ANF) Characteristics of Hyperbaric Nocturia Hydrostatic Pressure Effect on Active Na Transport Summary References. 117 118 123 131 131 133 133 135 135 135 136 140 142 142 Chapter 5 HEAD-OUT WATER IMMERSION: A CRITICAL EVALUATION OF THE GAUER-HENRY HYPOTHESIS J.A. Krasney, G. Hajduczok, K. Miki, J.R. Claybaugh, J.L. Sondeen, D.R. Pendergast and S.K. Hong Introduction.................. Water Immersion as a Model of Hypervolemia Species Effects on Water Immersion Responses Methodological Considerations of the WI Model. Cardiovascular Receptors. Cardiac Receptors.. Arterial Baroreceptors. Cardiovascular Effects of WI 147 149 152 154 155 155 158 160 ix

Hypervolemia in WI.... Regional Blood Flow in WI Renal Responses to WI.. Hormonal Responses to WI Vasopressin..... Renin and Aldosterone Secretion. Atrial Peptides...... Renal Prostaglandins... Circulating Catecholamines Role of the Renal Sympathetic Nerves Influence of Circadian Rhythms. Effects of Water Temperature Conclusions... Acknowledgements References.... 161 164 165 168 168 171 172 173 173 173 175 177 177 180 180 Chapter 6 FLUID AND ELECTROLYTE BALANCE AND HORMONAL RESPONSE TO THE HYPOXIC ENVIRONMENT l.r. Claybaugh, C.E. Wade and S.A. Cucinell Introduction............... Effects of Hypoxia on Water and Electrolyte Balance Evidence for Hypohydration at High Altitude Effects of High Altitude on Electrolytes.. Mechanisms of Hypoxia-Induced Hypohydration Effects of Hypoxia on Thirst and Mechanisms of Control Effects of Hypoxia on Urine Flow.... Inhibition of ADH in Response to Acute Mild Hypoxia Stimulation of ADH Release by Hypoxia. Effects of Hypoxia on Glucocorticoids. Mechanisms of Salt Imbalances...... Atrial Natriuretic Factor Responses to Hypoxia. Inhibition of Aldosterone by Hypoxia Hormones and Altitude Sicknesses.... 187 188 188 190 191 192 193 194 196 200 201 202 202 205 x

Summary.. References. 207 208 Chapter 7 HORMONAL REGULATION OF FLUID AND ELECTROLYTES DURING PROLONGED BED REST: IMPLICATIONS FOR MICROGRAVITY J.E. Greenleaf Introduction Bed Rest First day First month and beyond. Fluid Shifts in Microgravity Summary and Conclusions. Re ferences........ Index.... 215 216 216 223 226 229 230 233 xi