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ID 50000
file
creator
M. NAZIR AHMED
subject
Hypoxic pulmonary vasoconstriction
Chemoreceptors
Almitrine
Doxapram
Prostacyclin
Nifedipine
Dogs
NDC
Medical sciences
abstract
Almitrine bismesylate, a peripheral chemoreceptor stimulant has been shown to increase arterial oxygen tension in patients with chronic airflow obstruction. This effect is thought to be partly attributable to the enhancement of hypoxic pulmonary vasoconstriction (HPV). However, regarding this point the results of various clinical and animal studies on almitrine are inconclusive.
The aim of this study was to investigate the effect of almitrine on HPV in anesthetized, open chested dogs. HPV was expressed in terms of flow diversion associated with hypoxic challenge to the left lower lobe (LLL) where LLL and the rest of the lung were separately ventilated. Results showed that the HPV was enhanced by relatively lower doses of almitrine infusion while attenuated by higher doses. Stimulus-response curves (relationship between end-tidal oxygen pressure and LLL blood flow) showed shift to the right, indicating that almitrine induced the pulmonary vasoconstriction dose-dependently at progressively higher end-tidal oxygen tensions during LLL hypoxic challenges. This suggested that almitrine, also enhanced the response of pulmonary vessels to hypoxia. These changes were not found during almitrine vehicle infusion.
Plasma level of 6-keto-PGF1α, the stable metabolite of PGI2 did not show any significant changes after infusion of almitrine. Besides this, following denervation of peripheral chemoreceptors, some dogs showed the same effects as observed in those without chemoreceptor denervation i,e HPV was enhanced by low doses of almitrine and attenuated by higher doses where stimulus-response curves also shifted towards the right. Doxapram, another chemoreceptor stimulant drug did not enhance or attenuate HPV. The effect of almitrine was not influenced by blocking the Ca++ entry through the voltage dependent channel.
It was therefore concluded that vasoconstriction induced by almitrine may be attributed to a direct effect on pulmonary vessels rather than being mediated via the peripheral chemoreceptors.
description
This study was performed in the Second Department of Internal Medicine, Hiroshima University School of Medicine, under a scholarship granted by the Ministry of Education, Science and Culture (Monbusho), The Government of Japan.
journal title
Hiroshima Journal of Medical Sciences
volume
Volume 36
issue
Issue 4
start page
325
end page
346
date of issued
1987-12
publisher
Hiroshima University Medical Press
issn
0018-2052
ncid
pubmed id
language
eng
nii type
Departmental Bulletin Paper
HU type
Departmental Bulletin Papers
DCMI type
text
format
application/pdf
text version
publisher
department
Graduate School of Biomedical Science
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