We studied the accommodation of the increased pulmonary blood flow in the transition from rest through two successive levels of exercise in 19 awake mongrel dogs. We used the single bolus multiple indicator dilution technique with markers of the pulmonary vascular surface area and studied their behaviour at exercise. In a first set of experiments (n = 9) ($ sp3$H) norepinephrine served as the vascular surface area tracer while ($ sp3$H) benzoyl-Phe-Gly-Pro (($ sp3$H) BPGP), an inactive angiotensin-converting enzyme substrate was utilized in another (n = 10). Three other tracers were also injected with the surface markers: two vascular space markers, ($ sp{51}$Cr) erythrocytes and ($ sp{125}$I) albumin, and a water space tracer, ($ sp{14}$C) 1,8-octanediol. The mixture was injected into the pulmonary circulation and timed outflow samples were collected in the ascending aorta to obtain dilution curves. With exercise, the increase in pulmonary blood flow was accompanied by a linear increase in oxygen consumption. The range of blood flow achieved varied from 41 ml/s to 457 ml/s. The central blood volume as measured from the intravascular references increased linearly with flow. The tracer accessible extravascular lung water increased with flow and rapidly approached a maximal asymptotic proportion representing 75% of the postmortem lung weight. The ratio of the dilutional estimates of the extravascular lung water to that measured gravimetrically also increased in a similar fashion to reach an asymptotic proportion of close to 100%. These values were attained for moderate values of blood flow and did not increase further with higher blood flows. Tracer norepinephrine extractions at rest and at the two levels of exercise were 17% $ pm$ 1.2, 14% $ pm$ 0.8 and 15% $ pm$ 0.8 (SE) respectively. Using the Crone approximation we computed the permeability surface area product (PS) for norepinephrine. The PS product increased linearly with flow. Similarly, the proportional ($
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.70163 |
| Date | January 1990 |
| Creators | Dupuis, Jocelyn |
| 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 (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001214446, proquestno: AAINN67507, Theses scanned by UMI/ProQuest. |
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