Item – Theses Canada

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OCLC number
1017543201
Author
Watson, John D.(John Douglas),1959-
Title
A study of two peptides putatively involved in fluid homeostasis : 1. The 13.2-kDa (IP) subunit of NADH:ubiquinone oxidoreductase ; and ; 2. The antidiuretic peptide pneumadin.
Degree
Ph. D. -- Queen's University, 1994
Publisher
Ottawa : National Library of Canada = Bibliothèque nationale du Canada, 1995.
Description
3 microfiches
Notes
Includes bibliographical references.
Abstract
The hormonal mechanism of fluid and salt regulation in mammals is a complex and expanding field of study. The study reported in this thesis was an examination of two peptides putatively involved in fluid regulation. The protein sequence of the first of these was determined from an acid extract of rat heart and identified during this study as the 13.2-kDa (IP) subunit of NADH:ubiquinone oxidoreductase. Identification showed that our initial supposition was incorrect, since this peptide did not represent a fluid regulating hormone. The protein sequence was used to generate an oligonucleotide probe which allowed isolation of a cDNA coding for the rat homologue of 13.2-kDa (IP). Southern analysis indicated that the 13.2-kDa (IP) sequence exists as a single copy gene. The sequence of a genomic clone contained one intron and promoter elements including a TATAAA region. The 5$\sp\prime$ flanking region has regions similar to the nuclear respiratory factor-1 motif. The sequence from the rat has a high degree of identity with the mouse and cow homologues of this protein indicating that it is functionally important. The second part of this study involved the analysis of the recently discovered antidiuretic decapeptide pneumadin. Bolus intravenous injection of 5 nmol of synthetic pneumadin into a water-loaded rat caused a rapid and significant reduction in urine flow, and an associated significant reduction in Na$\sp+$ and Cl$\sp-$ excretion. Bolus intravenous injection of 20 nmol pneumadin into non-water-loaded rats caused a significant increase in arginine vasopressin 10 minutes postinjection which rapidly returned to basal levels. Injection of pneumadin into Brattleboro rats did not cause reduction of urine output. Radioiodinated pneumadin was rapidly cleared from the rat circulation, with a t$\sb{1/2}\beta$ of 480 seconds. Further, the radioiodinated pneumadin was modified in the rat blood. Amino acid sequencing of the modified pneumadin indicated that this modification was not proteolysis. Analysis of normal rat plasma by radioimmunoassay indicated that pneumadin was present. These data indicated that the mechanism by which pneumadin caused an antidiuresis is by stimulation of vasopressin release. Detection of pneumadin in normal rat plasma indicates that this antidiuretic peptide is a novel hormone.
ISBN
0315956690
9780315956698