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Paper Information

Title: 

EFFECTS OF ALVEOLAR HYPERCAPNIA ON HYPOXIC PULMONARY VASCULAR RESPONSES OF ISOLATED VENTILATED-PERFUSED RABBIT LUNG

Type: SPEECH
Author(s): KETABCHI F.*,DEHGHAN GHOLAM ABAS,SHID MOUSAVI SEYED MOSTAFA,WEISSMANN N.
 
 *DEPARTMENT OF PHYSIOLOGY, SHIRAZ UNIVERSITY OF MEDICAL SCIENCES, SHIRAZ, IRAN
 
Name of Seminar: IRANIAN CONGRESS OF PHYSIOLOGY AND PHARMACOLOGY
Type of Seminar:  CONGRESS
Sponsor:  PHYSIOLOGY AND PHARMACOLOGY SOCIETY, MASHHAD UNIVERSITY OF MEDICAL SCIENCE
Date:  2009Volume 19
 
 
Abstract: 

Acute respiratory disorders and permissive hypercapnic strategy may lead to alveolar hypoxia and hypercapnic acidosis. However, the effects of hypercapnia with or without acidosis on hypoxic pulmonary vasoconstriction (HPV) are controversial. We investigated the sequential effects of hypoxic-normocapnia, hypoxic-hypercapnic acidosis and hypoxic-hypercapnia with normal pH (Ph corrected with sodium bicarbonate) on HPV and capillary permeability in the isolated ventilated-perfused rabbit lung. No alteration in vascular tone was noted during normoxic-hypercapnia with or without acidosis as compared to normoxicnormocapnia. Hypoxic-hypercapnia with normal pH resulted in a transient increase in HPV during the course of sequential ventilation maneuvers while hypoxic-hypercapnic acidosis strengthened HPV over time. Hypoxichypercapnic acidosis also decreased exhaled NO more than hypoxic-hypercapnia with normal pH and hypoxic-normocapnia. However, inhibition of NO synthesis by Nitro-L-arginine (L-NNA) did not change HPV over time during hypoxichypercapnic acidosis, but there was an increase in HPV during hypoxichypercapnia with normal pH and hypoxic-normocapnia. There was an increase in capillary permeability during hypoxic-hypercapnia with normal pH, but not during hypoxic-hypercapnic acidosis. This response was NO dependent because it disappeared after L-NNA administration. Hypercapnia with or without acidosis influenced differently the triphasic hypoxic responses of pulmonary vasculature and permeability. These effects seem to be partially linked to NO-mediated pathways.

 
Keyword(s): HYPOXIA, HYPERCAPNIC ACIDOSIS, PH, CAPILLARY PERMEABILITY
 
 
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