Cardiac tamponade hypotension was produced in White Leghorn roosters by infusion of saline into the pericardial sac. Concomitant with the decrease in arterial pressure to 50 mm Hg, the central venous pressure increased 8-fold (up to 12 mm Hg). Despite this marked venous congestion the response to cardiac tamponade was characterized by a significant increase in plasma volume due to the influx of protein-poor interstitial fluid into the vasculature. The mechanisms underlying the hemodilution response in the roosters were markedly different from those involved in the hemodilution response to hypotension in mammals. The observed hemodilution was not mediated by a glucose osmotic gradient and did not appear to involve activation of the sympathoadrenal axis. The increase in central venous pressure was not transmitted to the microvasculature of skeletal muscle. The plasma volume expansion appeared to be due to passive transfer of the fall in arterial pressure to the microcirculation; this indicated a predominant arterial influence on the skeletal muscle microvasculature in the chicken. / Studies on the disruption of normal steady state hemodynamics in the rooster by pressure perturbations imposed by cardiac tamponade suggested that the regulation of normal fluid balance in the chicken was different from that in mammals. Summation of the steady state Starling parameters governing fluid exchange (capillary hydrostatic pressure + tissue oncotic pressure - plasma oncotic presure - tissue hydrostatic pressure) indicated a large imablance in favor of a net fluid filtration from the bloodstream. The maintenance of fluid balance in the chicken appears to involve factors other than those outlined by Starling.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.68501 |
| Date | January 1980 |
| Creators | Light, Margaret Jean Constable. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Pharmacology and Therapeutics) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000089966, proquestno: AAINK50492, Theses scanned by UMI/ProQuest. |
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