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Evaluation of P-Aminohippurate As a Marker for Blood-Flow Determinations in Cattle Denis Jay Meerdink Iowa State University

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Evaluation of P-Aminohippurate As a Marker for Blood-Flow Determinations in Cattle Denis Jay Meerdink Iowa State University Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1981 Evaluation of p-aminohippurate as a marker for blood-flow determinations in cattle Denis Jay Meerdink 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 Meerdink, Denis Jay, "Evaluation of p-aminohippurate as a marker for blood-flow determinations in cattle " (1981). Retrospective Theses and Dissertations. 7448. https://lib.dr.iastate.edu/rtd/7448 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]. INFORMATION TO USERS This was produced from a copy of a document sent to us for microfilming. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help you understand markings or notations which may appear on this reproduction. 1.The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure you of complete continuity. 2. When an image on the film is obliterated with a round black mark it is an indication that the film inspector noticed either blurred copy because of movement during exposure, or duplicate copy. Unless we meant to delete copyrighted materials that should not have been filmed, you will find a good image of the page in the adjacent frame. If copyrighted materials were deleted you will find a target note listing the pages in the adjacent frame. 3. When a map, drawing or chart, etc., is part of the material being photo­ graphed the photographer has followed a definite method in "sectioning" the material. It is customary to begin filming at the upper left hand corner of a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued again—beginning below the first row and continuing on until complete. 4. For any illustrations that cannot be reproduced satisfactorily by xerography, photographic prints can be purchased at additional cost and tipped into your xerographic copy. Requests can be made to our Dissertations Customer Services Department. 5. Some pages in any document may have indistinct print. In all cases we have filmed the best available copy. University Microfilms International 300 N. ZEEB RD., ANN ARBOR, Ml 48106 8209148 Meerdink, Denis Jay EVALUATION OF P-AMINOHIPPURATE AS A MARKER FOR BLOOD- FLOW DETERMINATIONS IN CATTLE Iowa State University PH.D. 1981 University Microfilms I nt6r n âtion&! 300 N.Zeeb Road, Ann Arbor, MI 48106 Evaluation of p-aminohippurate as a marker for blood-flow determinations in cattle by Denis Jay Meerdink A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Animal Science Major: Nutritional Physiology Approved: Members of the Committee: Signature was redacted for privacy. Signature was redacted for privacy. Signature was redacted for privacy. Signature was redacted for privacy. Iowa State University Ames, Iowa 1981 11 TABLE OF CONTENTS Page PREFACE 1 Format of Dissertation 2 PART I. DETERMINATION OF PARA-AMINOHIPPURIC ACID AND N-ACETYL-PARA-AMINOHIPPURIC ACID BY HIGH PRESSURE LIQUID CHROMATOGRAPHY 4 Introduction 4 Literature Review 4 Materials and Methods 7 Materials 7 Methods 8 Detection wavelength 8 Chromatographic conditions 10 Detector linearity 10 Deprotelnlzatlon 11 Barium hydroxide-zinc sulfate 11 Perchloric acid-potassium hydroxide 12 Peak-height evaluation 14 Results and Discussion 15 Detection wavelength 15 Chromatographic condlt^on^ 15 Detector linearity 18 Deprotelnlzatlon 18 Barium hydroxide-zinc sulfate 21 Perchloric acid-potassium hydroxide 22 Conclusions 27 PART II. PARA-AMINOHIPPURIC ACID IN VIVO 29 Literature Review 29 Some techniques for the determination of flow 29 Electromagnetic flowmeters 29 Ultrasound flowmeters 30 Thermal methods 31 Other methods 32 General limitations 34 Determination of blood flow by indicator-dilution 34 ill Page Renal transport of PAH 37 PAH clearances and kinetics in vivo 39 Metabolism of PAH 43 Materials and Methods 45 Experiments with non-radioactive PAH and aPAH 45 Single injections 45 Continuous infusions 48 Experiments with radioactive PAH 49 Results and Discussion 53 Experiments with non-radioactive PAH and aPAH 53 Single injection 53 Continuous infusion 55 General comments on the non-radioactive experiments. 56 Experiments with H-PAH 60 Conclusions 85 POSTSCRIPT 87 BIBLIOGRAPHY 88 ACKNOWLEDGEMENTS 98 APPENDIX A. PEAK-HEIGHT RATIO PROCEDURE FOR QUANTITATION OF PAH AND aPAH USING PAB AS AN INTERNAL STANDARD 99 APPENDIX B. EVANS BLUE PROCEDURE 101 APPENDIX C. PLOTS FOR SINGLE-INJECTION EXPERIMENTS USING UNLABELLED PAH AND aPAH 103 APPENDIX D. PLOTS FOR CONTINUOUS INFUSION EXPERIMENTS USING UNLABELLED PAH AND aPAH 158 1 PREFACE In recent years, much knowledge has been obtained about metabolism by investigating the in vivo kinetics of radioactively-labeled compounds. Much information is lacking, however, about changes of various compounds in metabolic diseases such as ketosis and about the role that specific organs have in altered metabolic states occuring in such diseases. Although concentrations of metabolites can be measured in blood and information is available regarding in vitro metabolic capacities, the physiological changes in metabolism cannot be described with confidence until information is obtained under physiological conditions. One way to assess the changes of metabolic adaptation is by trans-organ balances of Important metabolites. The trans-organ balance approach estimates fluxes of various metabolites in and out of organs of Interest by comparing blood entering and exiting the organ. The trans-organ balance method reveals changes in organ uptake and output of a metabolite regardless of a change, or lack of change, in systemic blood concentrations of that metabolite. A requirement of the trans-organ balance technique is an accurate quantitation of flow of blood that enters and exits organs to be studied. Fluxes are calculated from concentrations of the metabolite in blood and the rate of flow of blood through the organ. Therefore, small errors in determination of blood flow introduce errors in estimates of fluxes in spite of an accurate determination of metabolite concentration in blood. Dye-dilution techniques have been used successfully to determine flow of blood in vivo. These techniques involve Injection of an indicator or 2 marker and determination of dilution of that marker in sampled blood. Continuous-infusion techniques have an advantage for use in trans-organ balance studies in that the timing of collection of samples is not critical. Therefore, substantial errors in calculation of fluxes across organs can be avoided. An acceptable blood-flow marker must exhibit four qualities: (1) be rapidly and uniformly distributed in blood, (2) have no physiological or pharmacological action on the cardiovascular system that would affect the flow of blood, (3) be neither produced nor de­ stroyed within the blood stream, and (A) be easily detected. It was of interest to the Nutritional Physiology Group in the Department of Animal Science at Iowa State University to develop a dye- dilution method for determination of blood flow in experiments investi­ gating hepatic fluxes of metabolites in ruminant metabolism including ketosis, a metabolic disease common to lactating dairy cows. Format of Dissertation The research described in this dissertation has been divided into two parts. This two-part format is an attempt to present and discuss two distinct segments or goals of the research undertaken to evaluate para- am inohippurate (PAH) as a blood-flow marker to be used for trans-organ balance studies. 3 Part I is concerned with the development of an accurate, rapid method for quantitation of PAH and N-acetyl-p-aminohippurate (aPAH). Part II involves the in vivo observations of the kinetics and trans­ formations of PAH and aPAH. Each part contains its own Literature Review, Materials and Methods, Results and Disccusion, and Conclusion sections. 4 PART I. DETERMINATION OF PARA-AMINOHIPPURIC ACID AND N-ACETYL-PARA-AMINOHIPPURIC ACID BY HIGH PRESSURE LIQUID CHROMATOGRAPHY Introduction Para-amlnohippuric acid is well-suited for use as a blood-flow marker in trans-organ balance studies, especially for trans-liver balances, because it is not extracted by the liver (Katz & Bergman, 1969a) and is excreted only by the kidney (Blaufox, et al., 1963). Problems associated with analysis available for PAH needed to be overcome by development of a new analysis procedure. The problems will become apparent in the litera­ ture review that follows. Literature Review 4 PAH is an N -amino-substituted derivative of hippuric acid, and has been used for a variety of purposes in renal physiology and clinical medicine. The parent compound was termed "hippuric acid" after the site of its original discovery, horse urine. PAH perhaps is most closely identified with renal physiology because of its traditional use in the determination of renal plasma flow and of renal clearance. The first studies on excretion of hippuric acid deriv­ atives were carried out durinp the late 1930s and early 1940s (Elsom, et al., 1936; Smith, et al., 1938; Finkelstein, et al., 1941; and Smith, et al., 1945). Inconsistencies in clearance values of diodrast (3,4-diiodo-4-pyridone-N-acetate), another compound commonly used to 5 determine renal plasma flow and clearances, and of PAH prompted Newman, et al.
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