Exocrine Glands: Proceedings of a Satellite Symposium of the XXIV International Congress of Physiological Sciences 9781512800746

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EXOCRINE

GLANDS

Exocrine Glands Proceedings of a Satellite Symposium of the XXIV International Congress of Physiological Sciences EDITORS: STELLA Y. BOTELHO, M . D . F R A N K P . BROOKS, M . D . WALTER B . SHELLEY, M . D . ,

PHD.

1 UNIVERSITY OF PENNSYLVANIA P R E S S PHILADELPHIA 1969

Printed 1969 by the University of Pennsylvania Press. Copyright under the International Copyright Union. All rights reserved. This book is protected by copyright. No part of it may be duplicated or reproduced in any manner without written permission from the publisher. Made in the United States of America. University of Pennsylvania Press. Library of Congress catalogue number 72-97070 SBN: 8122-7606-X Printed in the United States

Participants

ANNE M. ABROMOVAGE, Hahnemann Medical College, Philadelphia, Pa. MARIO ALTAMIRANO, Universidad Central de Venezuela, Caracas, Venezuela JOHN E. BAER, Merck Institute for Therapeutic Research, West Point, Pa. F. K . BAGATELL, Squibb Institute for Medical Research, New Brunswick, N.J. HAROLD M. BATES, Wallace Laboratories, Cranbury, N.J. LYLE V. BECK, Indiana University, Bloomington, Indiana HERMAN BEERMAN, University of P e n n s y l v a n i a

ROBERT W. BERLINER, National Heart Institute, Bethesda, Maryland JOHN BIENENSTOCK, McMaster University, Hamilton, Ontario, Canada THOMAS F. BOAT, National Institute of Health, Bethesda, Maryland STELLA Y . BOTELHO, University of P e n n s y l v a n i a

G. E. BRIGHTENBACK, Merck Sharp and Dohme Research Laboratories, Rahway, N.J. FRANK P. BROOKS, University of P e n n s y l v a n i a WILLIAM J. BRUNTON, University of P e n n s y l v a n i a

SAUL W. BRUSILOW, Johns Hopkins University, Baltimore, Maryland A. S. V. BURGEN, Cambridge University, Cambridge, England CLYDE BURNETT, Revlon Incorporated, New York, New York R. M. CASE, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, England MICHAEL CHANG, Brandeis University, Waltham, Massachusetts HOWARD H. CHAUNCEY, Veterans Administration Central Office, Washington, D.C. MICHAEL CLARK, Philadelphia General Hospital, Philadelphia, Pa. C. DAWES, University of Manitoba, Winnipeg, Manitoba, Canada ANA DEPALAU, University of Panama, Republic of Panama E. C. DERENZO, Lederle Laboratories Division, Pearl River, New York S. J. DESALVA, Colgate Research Center, Piscataway, New Jersey RICHARD L. DOBSON, University of Oregon, Portland, Oregon V

vi /

Participants

DONALD

S.

DOUGLAS,

WILLIAM A . DUNSON,

George Washington University, Washington, D.C. Pennsylvania State University, University Park,

Pa. University of Pennsylvania P A T R I C I A E G G E N A , Mount Sinai School of Medicine, New York, New York W. B. ELVERS, New York, New York N I L S E M M E L I N , University of Lund, Lund, Sweden R A L P H P. F E L L E R , Veterans Administration Hospital, Boston, Massachusetts M I C H A E L E. F R I T Z , Emory University, Atlanta, Georgia N I L I O E. F U E N M A Y O R , University of Zulia, Maracaibo, Venezuela J. R. G A R R E T T , Kings College Hospital, London, England A R T H U R G O L D S T E I N , University of Pennsylvania C A R L A. G O R E S K Y , Montreal General Hospital, Montreal, Quebec, Canada R I C H A R D J . G R A N D , Massachusetts Institute of Technology, Cambridge, Mass. H . D A V I D H A L L , Vanderbilt University, Nashville, Tennessee A. A. HARPER, University of Newcastle-upon-Tyne, Newcastle-uponTyne, England B A S I L L . H E N R I Q U E S , Boston University, Boston, Massachusetts J O H N F. H E R N D O N , National Cystic Fibrosis Research Foundation, New York, N.Y. N . C. H I G H T O W E R , Scott and White Clinic, Temple, Texas M A B E L R. H O K I N , University of Wisconsin, Madison, Wisconsin K E N N E T H R. H O L D E N , Smith, Kline and French Laboratories, Philadelphia, Pa. J O S E P H H . H O L M E S , University of Colorado, Denver, Colorado M A R T I N HOROWITZ, New York Medical College, New York, New York A L B E R T O B. H O U S S A Y , Universidad de Buenos Aires, Buenos Aires, Argentina D U N C A N H U T C H E O N , New Jersey College of Medicine and Dentistry, Jersey City, New Jersey K I M I O I K A I , Johns Hopkins University, Baltimore, Maryland H E N R Y I. J A C O B Y , Merck Sharp and Dohme Research Laboratories, West Point, Pa. H E N R Y D . JANOWITZ, Mount Sinai School of Medicine, New York, New York H E N R Y EDINGER,

Participants

/ vii

College of Medicine, Milton S . Hershey Medicai Center, Pennsylvania State University, Hershey Pennsylvania. D A V I D M C E W A N J E N K I N S O N , Hannah Dairy Research Institute, Ayr, Scotland R O B E R T E . J O H N S O N , University of Illinois, Urbana, Illinois K R O N I S K A P U R , Cleveland, Ohio K O N - T A I L K H A W , Children's Hospital Medicai Center, Boston, Massachusetts L E O N KRAINTZ, University of British Columbia, Vancouver, B.C., Canada F. K R E U T Z E R , Catholic University, Nijmegen, Netherlands K A R L L A D E N , Gillette Research Institute, Washington, D.C. B E R N A R D R. LANDAU, Merck Institute for Therapeutic Research, Rahway, N.J. B E N M A R R LANMAN, Bristol-Myers Products, New York, New York A. K. LASCELLES, Institute of Animal Physiology, Babraham, Cambridge, England A R N O L D L I E B E R M A N , New York, New York N A T H A N LIFSON, University of Minnesota, Minneapolis, Minnesota T. M. LIN, Lilly Research Laboratories, Indianapolis, Indiana J . L . LINZELL, Institute of Animal Physiology, Babraham, Cambridge, England C H A R L E S C . LOBECK, University of Wisconsin, Madison, Wisconsin J A M E S F . LONG, Albany Medical College, Albany, New York W. L . L U E D D E R S , The Proctor and Gamble Company, Cincinnati, Ohio D O N A L F . M A G E E , Creighton University, Omaha, Nebraska F R A N K M A R C H E S E , Revlon Incorporated, New York, New York J . RICARDO M A R T I N E Z , University of El Salvador, San Salvador, El Salvador M A U R I C E W. M E Y E R , University of Minnesota, Minneapolis, Minnesota M A R T I N C. M I H M , JR., USPHS Hospital, Staten Island, New York G L E N N E . M O R T I M O R E , Milton S. Hershey Medical Center, Hershey, Pa. I N G R I T H D E Y R U P - O L S E N , University of Washington, Seattle, Washington J . C H A R L E S PALLAVICINI, National Institutes of Health, Bethesda, Maryland LARRY P A L M E R , University of Pennsylvania F R E D E R I C K M . P A R K I N S , University of Pennsylvania G. P E E T E R S , University of Ghent, Ghent, Belgium O L E H O L G E R P E T E R S E N , University of Copenhagen, Copenhagen, Denmark GRAHAM JEFFRIES,

viii /

Participants

F . PLOEGMAKERS,

Catholic University, Nijmegen, Netherlands University of Copenhagen, Copenhagen,

JORGEN HEDEMARK POULSEN,

Denmark R. M.

Mayo Clinic, Rochester, Minnesota R I C H A R D P . Q U A T R A L E , Gillette Research Institute, Washington, D.C. H O W A R D R E B E R , University of Pennsylvania M. T. RIBERA, Hospital Santa Cruz y San Pablo, Barcelona, Spain P E T E R T. R I D L E Y , Smith, Kline and French Laboratories, Philadelphia, Pa. G E R A L D I. R O T H , University of Pennsylvania S T E P H E N S . R O T H M A N , Harvard Medical School, Boston, Massachusetts K E N Z O S A T O , University of Oregon, Portland, Oregon H E R B E R T S C H A P I R O , University of Tennessee, Memphis, Tennessee C H A R L O T T E S C H N E Y E R , University of Alabama, Birmingham, Alabama L E O N H. S C H N E Y E R , University of Alabama, Birmingham, Alabama I R E N E SCHULZ, Max-Planck-Institut fur Biophysik, Frankfurt, Germany I R V I N G L . S C H W A R T Z , Mount Sinai School of Medicine, New York, New York T H O M A S S C R A T C H E R D , University of Newcastle-upon-Tyne, Newcastleupon-Tyne, England E R N E S T S . S E A R S , JR., University of Texas, Dallas, Texas A L B E R T W . S E D A R , Jefferson Medical College, Philadelphia, Pa. P A U L E T T E S E T T L E R , University of Pennsylvania I R A L. S H A N N O N , Veterans Administration Hospital, Houston, Texas W A L T E R B . S H E L L E Y , University of Pennsylvania J . F. G. S L E G E R S , Catholic University, Nijmegen, Netherlands E D W I N L. SMITH, University of Texas, Houston, Texas L E I F S O L B E R G , University of Pennsylvania R O G E R D. S O L O W A Y , University of Pennsylvania I S A A C S T A R R , University of Pennsylvania R I C H A R D P. S U D D I C K , Creighton University, Omaha, Nebraska R I C H A R D T A Y L O R , University of Oregon, Portland, Oregon E. C L I N T O N T E X T E R , JR., Scott and White Clinic, Temple, Texas N I E L S A. T H O R N , University of Copenhagen, Copenhagen, Denmark P H I L I P T O S K E S , University of Pennsylvania H. C. V A N P R O O Y E N , Catholic University, Nijmegen, Netherlands M O R T O N B . W A I T Z M A N , Emory University, Atlanta, Georgia J O E R . W A R D E L L , JR., Smith, Kline and French Laboratories, Philadelphia, Pa. PRESHAW,

Participants University of Medicai College A N N W E C H S L E R , McGill University, J O H N I. W H I T E , Baltimore College of land GEORGE PAUL

D.

D.

WEBSTER,

WEBSTER,

VIRGIL WIEBELHAUS,

/ ix

Pennsylvania of Georgia, Augusta, Georgia Montreal, Quebec, Canada Dental Surgery, Baltimore, Mary-

Smith, Kline and French Laboratories, Philadel-

phia, Pa. National Institutes of Health, Bethesda, Maryland J. H. WILLS, Albany Medical College, Albany, New York J O S E P H A. W I T K O W S K I , University of Pennsylvania E U R I P I D E S Y I A C A S , Squibb Institute for Medical Research, New Brunswich, N.J. ULRICH WIESMANN,

Preface

IT IS fitting that I give you a brief background for the decision of the University of Pennsylvania to sponsor this Symposium on the Exocrine Glands. The idea originated with and was developed by the members of the program committee, who are also the editors of these Proceedings. In 1960, much of what was then known about secretion of the various exocrine glands was summarized by H. H. Ussing, J. H. Thaysen and N. A. Thorn (Handbuch der Experimentellen Pharmakologie: The Alkali Metal Ions in Biology, Springer-Verlag, Berlin, 1960). Since that time, the number of investigators who have been concerned with the mechanism of secretion and the control of secretion by the exocrine glands has greatly increased. However, except for a conference on the salivary glands, which was held in 1966, there has been little opportunity for those studying the various exocrine glands to meet to exchange experience and ideas. It was, therefore, decided to bring together the foremost workers in the field, to summarize and record our present knowledge and to set the direction for future research. I feel sure that this symposium will accomplish these purposes. PAUL NEMIR, JR.

Director, Division of Graduate Medicine, University of Pennsylvania, School of Medicine

xi

Acknowledgment

WE THANK Dr. Paul Nemir, Jr. and his staff for making possible the Symposium on the Exocrine Glands and these Proceedings; Emily Brooks and Marguerite Shelley for planning and executing the social activities for our colleagues from overseas and their wives; the editors of the various publications, who have permitted reproduction of illustrations and tables as indicated in the text; and all the participants, who made the Symposium interesting, informative and well worth the labor entailed. We are especially grateful to Dr. Graham Jefifries and Professor Ferdinand Kreuzer for ably substituting for ailing colleagues. We apologize if the list of participants includes some who were unable to attend the Symposium and does not include others who were present. STELLA Y . BOTELHO F R A N K P. B R O O K S W A L T E R B . SHELLEY

xiii

Contents xix

Introduction A. S. V. BURGEN

Section I. Secretion of Electrolytes and Water 1. Salivary Gland Secretory Transmembrane potentials and Electrolyte Transients in Salivary Glands

3

OLE HOLGER P E T E R S E N AND JORGEN HEDEMARK POULSEN

Water and Electrolyte Secretion by the Submaxillary Gland

20

J . RICARDO MARTINEZ

Observations on Secretory Potentials in Rat Submaxillary Gland

30

LEON H. S C H N E Y E R

Discussion

34

STELLA Y. BOTELHO, A. S. V. BURGEN, HOWARD H. CHAUNCEY, MICHAEL E . FRITZ, BASIL L. HENRIQUES, J . RICARDO MARTINEZ, OLE HOLGAR P E T E R S E N , LEON H. S C H N E Y E R ( d i s c u s s i o n l e a d e r ) , NIELS A. THORN

2.

Pancreas Water and Electrolyte Secretion by the pancreas

39

R. M. CASE, A. A. HARPER AND T. SCRATCHERD

Discussion

57

A. S. V. BURGEN, MABEL R. HOKIN, HENRY D. JANOWITZ

(discussion leader),

STEPHEN S. ROTHMAN,

THOMAS SCRATCHERD

Micropuncture Studies of the Pancreas of the Rabbit

61

IRENE SCHULTZ

Discussion

68

HOWARD A. R E B E R xv

xvi / Contents 3. Salt Gland Electrolyte Transport in the Avian Salt Gland

73

MABEL R. HOKIN

Reptilian Salt Glands

83

WILLIAM A. DUNSON

101

Discussion JOHN BIENENSTOCK, RICHARD L. DOBSON, WILLIAM A. DUNSON

(discussion leader),

MABEL R. HOKIN

4. Sweat Gland The Excretion of Solutes in Human Eccrine Sweat

105

ROBERT E. JOHNSON, TAKETOCHI MORIMOTO AND FRANCES D. ROBBINS

Discussion

125

SAUL W. BRUSILOW, RICHARD L. DOBSON

leader)

(discussion

IRENE SCHULTZ

Section II. Secretion of Organic Substances 5. Sweat Gland Mechanisms of non-electrolyte transport through epithelial cells

133

J. F. G. SLEGERS

Discussion

146

S. BRUSILOW

6. Pancreas Hormonal Control of Pancreatic and Acinar Cell Metabolism

153

PAUL D. WEBSTER, III

Transport of Protein by Pancreatic Acinar Cells: Random or Select

169

STEPHEN S. ROTHMAN

Discussion MABEL R. HOKIN, GRAHAM JEFFRIES

181 (discussion leader),

DONAL F. MAGEE, STEPHEN S. ROTHMAN, NIELS A. THORN, PAUL D. WEBSTER, III

Contents / xvii 7. Salivary Gland The Secretion of Immunoglobulins by the Human Salivary Glands

187

J . BIENENSTOCK, D. TOURVILLE AND T. B. TOMASI, J R .

Discussion

194

JOHN BIENENSTOCK, STELLA Y. BOTELHO, FRANK

p.

BROOKS

(discussion leader), c.

DAWES,

MICHAEL E. FRITZ, A. A. HARPER, A. K. LASCELLES, CHARLOTTE SCHNEYER, ULRICH WIESMANN

Section III. Neural, Hormonal and Pharmacological Control of Secretion 8. Sweat Gland Sweat Gland Function in Domestic Animals D. McEWAN JENKINSON

Discussion

201 216

SAUL W. BRUSILOW, RICHARD L. DOBSON, RICHARD J . GRAND, D. McEWAN JENKINSON, R O B E R T E. JOHNSON, WALTER B . S H E L L E Y

(discussion leader)

9. Salivary and Lacrimal Glands Neural Control of Salivary Glands

223

NILS EMMELIN

The Effects of Autonomic Nerve Impulses and Autonomic Drugs on Secretion by the Lacrimal Gland 227

STELLA Y . BOTELHO, ARTHUR M. GOLDSTEIN AND MITUHIKO HISADA

Discussion A. s. v. BURGEN (discussion leader),

239 NILS EMMELIN,

MICHAEL E. FRITZ, J . R. GARRETT, ALBERTO B. HOUSSAY, D. McEWAN JENKINSON, LEON KRAINTZ, J . L. LINZELL, THOMAS SCRATCHERD, NIELS A. THORN

10. Pancreas and Liver Duodenal Acidification and the Release of Secretin R. w . PRESHAW

Vagal Stimulation of Bile Flow in Conscious Dogs FRANK P. BROOKS AND MORTON I. GROSSMAN

247 253

xviii / Contents Discussion

275

FRANK P. BROOKS, A. A. H A R P E R , H E N R Y D. J A N O W I T Z

(discussion leader),

T. M. LIN, J A M E S F. LONG,

DONAL F. M A G E E , R. M. P R E S H A W , THOMAS S C R A T C H E R D

Summarization BY A. S. V. B U R G E N

281

Introduction

I WOULD like to make a few general points about this meeting to begin with. While this is a Symposium on Exocrine Glands, the definition of what constitutes such a gland is quite arbitrary. For instance the mammary gland is usually excluded as being more pertinent to the reproductive system, but I am glad to see some specialists in lactation here today. The kidney is also excluded from the daytime presentation, mainly because so much work is done on this organ that it is usually the subject of separate meetings. However, we are fortunate to have included in our post prandial program a talk by Dr. Robert Berliner on the renal tubule. This will keep us in perspective. These exclusions do serve to remind us that in a meeting like this a good deal of our effort is concerned with looking for common mechanisms in secretory processes. It is dismaying to find that there are striking differences in these processes not only between different secretory organs but also between the same organ in different species; a reminder that in evolution it is frequently the case that more than one solution has been found to be a biological problem. Exocrine glands offer as many unsolved challenging problems as any branch of physiology and I would like to point out just a few areas in which we need to see developments. The details of ion transport remain very obscure indeed for despite a great deal of work, we do not know which ions are actively transported and which follow passively; whether ion pair movements occur or ion exchange; we are even unsure whether the active transport processes are into or out of the cells. We know that nearly all exocrine glands secrete relatively high concentrations of potassium, yet no one has so far been able to suggest any reasonable functional significance for this. How is the actual secretory process controlled? The innervated and accessible face of secreting cells is the basal surface, yet secretion emerges from the cell apex, does this mean the intervention of the intracellular messenger, or is the primary secretogogue able to affect the apical cell membrane directly? Just as puzzling are the mechanisms xix

xx / Introduction by which macromolecules leave cells, whether individual secretory products are separately packaged and selectively released or whether the composition of the secretion merely reflects the previous commerce of the cell. I will end with a little collection of exocrine curiosities: Why do some of the secreted mucopolysaccharides have blood group specificity? Is this of functional significance? Why do many exocrine glands secrete factors relevant to the blood clotting process—not into the blood but in their secretions? Is Kallikrein concerned with regulating blood flow in salivary glands or merely with hoodwinking physiologists? What is a potent factor concerned with nerve growth doing in mouse salivary glands, particularly in the male? These are just a handful of enigmas that these glands pose and the members of this Symposium will leave with a feeling of gratitude if light is thrown on any of them. A . S. V . BURGEN Department

of

University of Cambridge,

Pharmacology, Cambridge,

England.

EXOCRINE GLANDS

Section 1 Secretion of Electrolytes and Water

Chairman:

RICHARD L. DOBSON

Professor and Chairman of Dermatology University of Oregon Portland, Oregon

1. Salivary Gland Secretory Transmembrane Potentials and Electrolyte Transients in Salivary Glands OLE HOLGER P E T E R S E N AND JORGEN HEDEMARK POULSEN*

THE formation of the secretion in most salivary glands can roughly be described as a two-step process. In the acinar-intercalated duct region a primary secretion with a composition close to an ultrafiltrate of plasma with respect to the concentrations of sodium, potassium, and chloride is produced (15,23,25). This primary secretion is modified in the duct system by a reabsorption of sodium chloride and secretion of potassium (25,26). The reabsorption of sodium chloride is only accompanied by very small amounts of water (26). It is generally assumed that all fluid secretion in the salivary glands occurs in the acinar-intercalated duct region (27). Therefore, the salivary secretory rate may be regarded as a measure of the rate of formation of the primary secretion. The present work was undertaken to obtain information about the mechanisms underlying the formation of the primary secretion, the mechanism and the function of the secretory transmembrane potential in the acinus and the sodium and potassium transients in the saliva and the venous outflow and their relations to the secretory process. All the experiments were carried out on the cat submandibular gland. The 'Institute of Medical Physiology C, University of Copenhagen, Denmark, Copenhagen. This work was supported by the Danish State Research Foundation, The Danish Foundation for the Advancement of Medical Science, and the Nordisk Insulinfond. We wish to: express our deep gratitude to Professor N. A. Thorn who suggested this project and whose never failing interest and valuable criticisms have been of great importance for us; thank Professor A. Lundberg (University of Goteborg) for many important discussions and suggestions, and Professor C. Crone for valuable suggestions; and gratefully acknowledge the excellent technical assistance of Mrs. Mona Ryberg. 3

4 / Secretion

Water

1.0 70 2.0

5.5

5.5 59

TEA Locke's solution

6.0

2.4 0.6 1.5

2.4 0.6 1.5

2.4 0.6 1.5

1.0

1.0

1.0

Control Locke's solution

2.4 0.6

4.0 2.4 0.6

Lithium Locke's solution

1.5 1.0

Nitrate Locke's solution

140 4.0 2.4 0.6

Sulphate Locke's solution

NaCl KC1 Na2HP04 NaH2P04 K2HPO4 KH2PO4 CaCL; Ca(N0 3 ) 2 MgCL, MgS0 4 Na2S04 NaN03 K2SO4 LiCI TEAC1 Glucose Sucrose

and

The Composition of the Perfusion Fluids (mM) Control Locke's solution

TABLE I:

of Electrolytes

142

1.5 1.0 140

142 5.5

5.5

5.5

142 5.5

composition of the perfusion fluids used in the experiments on artificially perfused glands is shown in Table I. The dependence

of the secretory

rate

on the composition

of the

extracellular fluid. The formation of saliva must be due to active transport mechanisms since it has been shown that salivary glands can secrete against pressures which are higher than the systolic arterial pressure (9). It would therefore be expected that metabolic inhibitors like cyanide should be able to abolish secretion. This has been shown to be true (6,19). These studies do not, however, yield any information about which kind of transport mechanisms are involved. g-Strophanthin is an inhibitor of active sodium transport and we found that it rapidly abolishes the secretion of the cat submandibular gland perfused with normal Locke's solution (Fig. 1). However, acetazolamide, which is an inhibitor of active chloride transport in the gastric mucosa (5) and in the frog cornea (8), also inhibits the salivary secretory rate (16). These inhibitor studies thus seem to indicate that both a sodium and a chloride transport is involved in the formation of the primary secretion. In experiments on artificially perfused glands it was seen that the secretory rate is very much dependent on the ionic composition of the extracellular fluid. When sulfate is substituted for chloride the secretion

Salivary Gland / 5 DROPS 7i

, G-STROPHANTI do" 4 *) I i

P 3 kI 521 it* ut ,. -I5

10 TIME

i

15

i—T MINUTES 20

FIG. 1. Inhibition of secretion by g-Strophanthin (ouabain) in the cat submandibular gland perfused with normal Locke's solution. Each circle represents the number of drops of saliva secreted after intraarterial injection of 5 fig Acetylcholine (ACh). (From Acta physiolog. Scand. 71: 194, 1967.)

is rapidly abolished (Fig. 2) and when nitrate is substituted for chloride the secretion nearly stops (13). When either lithium (Fig. 3) or tetraethylammonium (TEA) is substituted for sodium, the secretion is rapidly abolished. When 50% of the sodium is replaced by either lithium or TEA the secretory rate is markedly reduced (Fig. 4) whereas, when 50% of the chloride is replaced by either nitrate or sulfate the secretory rate is not affected very much. These findings seem to indicate that the formation of the primary secretion is dependent on both active sodium and active chloride transport mechanisms. The dependence of the size of the secretory potential on the composition of the extracellular fluid. The secretory potential in the acinar cells is the hyperpolarization of the contraluminal cell membrane which occurs when a salivary gland is stimulated (10,11). It has already been shown by Lundberg (12) that the secretory potential is due to an active ion transport since the size of the secretory potential was independent of the level of the resting membrane potential. This was confirmed by the fact that inhibitors of active transport abolish the secretory potentials in the cat submandibular gland perfused with normal Locke's solution, e.g., dinitrophenol (DNP) inhibits the secretory potentials (Fig. 5). In addition to DNP, g-Strophanthin, cyanide, and acetazolamide have been shown to inhibit the secretory potentials (16,19).

6 / Secretion of Electrolytes and Water SO,

Control mV _ 30 0 1 20 8

°o O