Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1980 Cardiovascular responses to diving in the turtle, Pseudemys scripta Stuart Keith Ware Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Animal Sciences Commons, Physiology Commons, and the Veterinary Physiology Commons Recommended Citation Ware, Stuart Keith, "Cardiovascular responses to diving in the turtle, Pseudemys scripta " (1980). Retrospective Theses and Dissertations. 6813. https://lib.dr.iastate.edu/rtd/6813 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. 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ZEEB ROAD, ANN ARBOR, Ml 48106 18 BEDFORD ROW, LONDON WCl R 4EJ, ENGLAND 8028642 WARE, STUART KEITH 1 /->/-->» -T a T\ T>T^r»T-\/-\>.ir«r^r« '-r-z-N tni rf VT fx: Tî Tin TO T"! TO \^/MS.UlW V/\:5UU1-/AI\ j\C^rwi\OCÙ l W i-/jvii>vj X1> iCiC. : i PSEUDEMYS SCRIPTA Iowa Slate University PH.D. 1980 University Microfilms 1 nt0r nBt i O n âl 300 N. Zeeb Road, Ann Arbor. MI 48106 18 Bedford Row, London WCIR 4E]. England Cardiovascular responses to diving in the turtle, Pseudemys scripta by Stuart Keith Ware A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Zoology Major: Zoology (Physiology) Approved: Signature was redacted for privacy. n Char/^e of Major Work Signature was redacted for privacy. For the Major DepartmentIT Signature was redacted for privacy. 5 V ! U! WW WW « w i » v.-^v- ? ^ ^ Am ^ ^^ 1UWG O UC UC u 11 I V c: o I u j Arnes, 1980 ii TABLE OF CONTENTS page INTRODUCTION 1 REVIEW OF THE LITERATURE 3 Historical Perspective 3 Respiratory System and Metabolism 6 Cardiovascular System 22 Nervous System and the Integration of Physiological Responses to Diving /2 MATERIALS AND METHODS 37 Animal Maintenance 87 Heart Rates, Electrocardiograms and Blood Pressures 87 Hardiac Output, Shunting and Tissue Blood Flow 92 RESULTS 104 Heart Rates, Electrocardiograms and Blood Pressures 104 Cardiac Output, Shunting and Tissue Blood Flow 132 r\rr*r*}te*r'rr\\iUlOVUOOlUn SUMMARY 177 LITERATURE CITED 180 ACKNOWLEDGEMENTS 204 1 INTRODUCTION The physiological responses elicited when animals dive or are experi­ mentally submerged have been of interest to zoologists for many years. Since 1870, studies have been carried out to elucidate these responses in an attempt to explain the long dives made by natural divers. As a result, we now understand many of the circulatory and respiratory adaptations which allow for long, and sometimes deep, dives. The results have im- vci: ivc uc jVMU G * & vW M ty i u: a:i uuuc: ^ oauu liiy v : u: ic ptij^iuswyi^ai i c— sponses to submergence per se. There are situations, of much more immedi­ ate interest and importance than diving itself, which, apparently, elicit a physiological response not unlike the response to submersion in divers. Such situations include birth, trauma such as shock, burns, surgery, hemorrhage or cardiac failure. It appears that the physiological mecha­ nisms employed by natural divers to remain submerged for prolonged time periods are present in all vertebrates during all stages of life and may simply be the perfection of a corraion defense mechanism against asphyxie condi tions. Despite all the information available on the physiology of diving, comparatively little is known about lower vertebrates. Mammals and birds have been studied extensively, but it is not known to exactly what extent Tra H 1 rtn i.fX 4 X -yc. -r yi &v~rr:c n :: c aX r? 4 \ / •? « rt » X. T? lûC^ ^ 3 I T— 11y» 3/4/44^4I V I vrw-: 11 ) III».* itjr/ wr\^ I ^iis»In o w 41« *f 4I wy • •SiMVs» Kooîn Hnna^wtiw nnI é «-/ * \w/r\riHor! W t Vf \rov^*^ûKv»a4-oçVWt W * L»pv*o « ^ /-'rs*nrl4/-»+4*^nt t ovp»r»nloVa^/xCklll^tC) turtles have been shown to show a reduction in heart rate upon diving by most workers, but not by all - even when the same species was used. The 2 situation is even more confusing with amphibians where, apparently, the cardiac response varies with water oxygen content, temperature, species used, and furthermore, may be seasonal. Based on indirect evidence, tur­ tles have been reported to show either reduced blood flow or maintained blood flow to muscles during submergence. No direct measurements of tis­ sue blood flow in any diving reptile have been attempted. In fact, cir­ culatory studies of any nature for diving amphibians or reptiles are scarce. It was the purpose of this study, therefore, to measure the cardio­ vascular responses to submersion in the turtle, Pseudemys scripta. This animal was chosen because of its availability, size, and relative ease of surgical manipulation. Furthermore, more physiological information is available for this turtle species than for any other. The overall study was divided into two parts. The first part was con­ cerned with measurements of heart rates, electrocardiograms, blood pres­ sures and external respiration. These parameters were recorded from vu I un ud r I I V uivjjiu uu r u i o a:> we i-1 ai» i rmn cm nna i cAucf inicfi i » v 5UU- merged. The second part of the study involved measurements of cardiac output, stroke volume, intra-cardiac shunting of blood, and blood flow to various tissues. Due to the nature of these procedures^ voluntarily div­ ing turtles could not be studied. 3 REVIEW OF THE LITERATURE Historical Perspective Studies into the physiology of diving began over 100 years ago with the work of the French physiologist Paul Bert (1870). Although there had been earlier mention in the literature of the ability of divers to sur­ vive prolonged submersion, Bert was the first investigator to try to ex­ plain this phenomenon. He is, therefore, considered by most workers as the founder of diving physiology. Bert attempted to explain the differ­ ence between divers and non-divers by comparing the hen and the duck. He felt that the difference between the two species which allowed the duck to remain submerged for a longer time than the hen (15 minutes vs. 3 minutes) was the fact that the duck had a greater blood volume per unit body weight (10%) than the hen (4%). Thus, the duck had a greater oxygen store to draw upon during diving. Performing the crude experiment of bleeding the duck until its blood volume/body weight ratio had been reduced to that of the hen, he demonstrated that the ability to dive had decreased corres­ pondingly. Twenty-four years later Bert's conclusion was challenged by another French physiologist, Charles Richet (1894a). He argued that, even though the duck did have a larger weight-specific blood volume than the hen, -rV-.-- c Civ-f-v-a n\r\rt~.ci!r. -...'n : Tr. macr f ha !-..Qar; Ç r.T a 1 nnn Hiup. Analysis of gas in the respiratory system of diving clucks (Langlois and Richet, 1898) shewed that oxygen consumption decreased during submergence. Furthermore, Richet (1399; showed that immersion itself was important to survival during respiratory arrest. Tracheal occlusion in two groups of 4 ducks demonstrated that those which were immersed lived about three times as long as those left in the air. Richet concluded that physiological ad­ justments to submergence take place which cause a decrease in oxygen con- ciimn+imn THi< tha qiihmornnrl Hiirtn pyi 1 nnqfir on nyvnon stores available than those left to perish in air.