Effects of ANG II and its receptor blockers on nasal salt gland secretion and arterial blood pressure in conscious Pekin ducks (Anas platyrhynchos). Roham Zandevakili A thesis submitted in conformity with the requirements for the degree of Master of Science Graduate Department of Zoology University of Toronto @ Roham Zandevakili 1998 National Library Bibliothèque nationale du Canada Acquisitions and Acquisitions et Bibliographic Services services bibliographiques 395 Wellington Street 395, nie Wellington OttawaON KlAON4 Ottawa ON K1 A ON4 Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sel1 reproduire, prêter, distribuer ou copies of this thesis in microfonn, vendre des copies de cette thèse sous paper or electronic formats. la fonne de microfiche/film, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in Ulis thesis. 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TABLE OF CONTENT TABLE OF CONTENTS .................................................................................................... i ACKNOWLEDGEMENTS ...............................................................................................iv LIST OF FIGURES ............................................................................................................. v ..* LIST OF TABLES ..............: ........................................................................................... vil1 LIST OF ABBREVIATIONS ............................................................................................ ix INTRODUCTION .......................................................................................................... 1 Objectives.............................................................................................................. 2 The Renin Angiotensin System.......................................................................... 3 Blood Pressure Regulation ......................................................................................7 Life in a Marine Environment ................................................................................. 9 Vertebrate Osmoregulation ...................................................................................1 1 Avian Osmoregulation.. ............................................................................ 12 a) The avian renal-cloaca1 system ........................................................... 12 b) Avian nasal sait glands ......................................................................... 13 MATERIALS AND METHODS ...................................................................................16 RESULTS ........................................................................................................................ -23 Nasal Salt Glands ..................................................................................................24 Blood Pressure Experiments ................................................................................. 4 DISCUSSION ...................................................................................................................52 Nasal Salt Gland Response to ANG II and III .......................................................54 Ionic Concentrations of the Nasal Salt Gland Fluid ..............................................55 Characteristics of ANG 11 Receptors .....................................................................58 Effect of SARILE on Nasal Salt Glands and the Cardiovascular System ............. 59 Effect of Mammalian ATI and AT2 Receptor Blockers ........................................61 FUTURE WSEARCH .....................................................................................................65 LITERATURE CITED .....................................................................................................66 ABSTRACT The vertebrate renin-angiotensin system (RAS) controls cardiovascular, rend and osmoregulatory functions. Angiotensin II (ANG Ii) is the most potent hormone of the RAS. However in some vertebrates, Angiotensin IQ (wa14]-AN~IiI) also has significant activity. The effects of angiotensins with different amino acid sequences and mamrnalian ANG II receptor antagonists on nasal salt gland function and arterial blood pressure in conscious white Pekin ducks were investigated in the present shtdy. There was a positive linear correlation: between nasal fiuid [Na7 and osmolality, between [Na+] and [KCI and between the rate of nasal salt gland fluid secretion (NFS) and [Na+] and [K"]. [A~~',V~I~]-ANGII (1 nrn01.k~" i.v.) inhibited NFS but did not change ionic concentrations. [v~~~]-ANGIII (1 or 5 nrn01.k~-')and ANG I (1-7) (20 nrn01.k~-')had no effect on NFS. SARI[LE acted as an ANG II receptor agonist and resulted in a prolonged and complete inhibition of NFS. The ATl receptor antagonist-losartan (DuP 753) and the AT2 receptor antagonist-PD 123319 both failed to block the inhibitory effect of [AS~~,V~~~]-ANGII on the nasal salt glands. AS^' ,v~~']-ANGII (2 nmol.kg" i.v.) increased mean arterial blood pressure by about 40 % (MABP) whereas the sarne dose of [AS~',V~~~]-ANGII (teleost) had only 30% of the pressor effect of [AS~',V~~~]-ANGII . Neither 1 nor 5 nrn01.k~-'of [V~I~I-ANGIII i.v. nor 20 nrn01.k~" of ANG I (1-7) had any measurable effect on MABP. SARILE completely blocked the pressor response to [AS~',V~~~]-ANGII, but the ATI antagonists losartan and CGP 48933 and the AT2 antagonist PD 123319 al1 failed to block the pressor response to [AS~',V~~~]-ANG Ir. iii AOWLEDGEMENTS ' 1 am very thankful to my parents, Ehteram and Gholamali, whose moral support and understanding of the demanding life of a graduate student was invaluable. It has been an unforgettable experience to work in Dr. Butler's lab. The arnount of knowledge gained was immense. I take great pride to have leamed my surgical skills from one of the best in the field of animal surgery, Dr. Butler. The past two years taught me that hard work usually results in success. It has been the hard work that made it possible for me to travel to Spain for a conference and meet the keynote speaker Prof. Knüt Schmidt-Neilsen who discovered the function of nasal salt gland. It was the highlight of my years in the Department of Zoology. During the ups and downs in the lab, it h& been the support of my good colleague, Donald Bang, that would always lift my spirit. He was always ready to help and gave fieely his insightful ideas. Thank you Don. 1 am thankful to many people in the Department who went beyond their duties to help me, and they include: Terry, Sonia, Kim, Ed, Louisa, Liz, Susan, Marie, Peter, Diana, Rosana, Jim, Ziggy, Lu, Eric, Rudy, Fred, Ray, Norman, Daniel, Scott, Steve S., Steve C., Janet, also Sharon and Christie for guiding me in the right direction, al1 the way from my undergraduate years. Finally I thank Dr. D.G.Butler for his training and patience. 1 greatly appreciate Dr. R. Stephenson's, Dr. L. Buck's, and Dr. H.H. Harvey's criticism and useful advice. Lastly, but not least, Dr. Gavin Oudit and Ms. Cadinouche for having prepared me for research in Dr. Butler's lab. Special thanks to Ms. Anoush Migirdicyan and Ms. Sun-Hee Pak for helping me with the long and tedious analytical procedures and proof-reading my thesis. LIST OF F'IGUIRES Figure 1. Avian angiotensin biosynthesis ..................................................................... 4,5 Figure 2A. Positive linear correlation between [Na+] and osmolaiity of fluid secreted by the nasal salt glands (Y = 1.61X + 153.1;r = 0.87; n = 334;Pe0.001). .......................... 25, 26 Figure 2B. Positive linear relationship between the rate of nasal fluid secretion (d.kg-'.5min-') and the [~a+](Y = 170.5X + 5 1 1.3; r = 0.48;n=334; Pc0.001)............................... 25 26 Figure 3A. Positive linear correlation between the rate of nasal fluid secretion (rnl.kg". 5 min") and the [K+] (Y = 4.83X + 12.25; r = 0.41; n = 334; P<0.001)................................. 27, 28 Figure 3B. Positive linear correlation between the nasal fluid mat] and [K*](Y = 0.025X - 0.45;r = 0.76;n = 334; P<û.001)............................................................................... 27, 28 Figure 4. Effects of [AS~',V~~~]-ANGII and [V~~~J-ANG III on nasal salt gland secretion in freshwater Pekin ducks during an i.v. infusion of hypertonie saline (1000 mosmol.kg-l) at a rate of 0.97 ml.rnin 'l. Values arerneans andS.E.M. n = 5. ...........................................3 31 Figure 5. Effects of ANG 1 (1-7) and [AS~',V~I~]-ANGII on nasal salt gland secretion during an i.v. inhision of hypeaonic saline (1000 rnosm01.k~-')at a rate of 0.97 ml.min 'l. Values are means and S.E.M. n = 5. ..........................................................................................., 34 Figure 6A. Effects of the mammalian angiotensin antagonist SARZLE on nasal salt gland secretion and the response by the nasal sdt glands to two i.v. injections of [AS~',V~~~]-ANG II given before and after the antagonist. Values are means and S.E.M.n=5. ........... 35, 36 Figure 6B. Pressor