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Title: Ontogenic changes in porcine pulmonary vascular and airway smooth muscle responsiveness in vitro
Author: Wilson, Louise Elizabeth
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1995
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The goals of these studies were to determine if maturational changes occurred in the responsiveness of airway and vascular porcine smooth muscle in vitro. Pulmonary arteries from immature pigs were less responsive than those from adult pigs to adrenoreceptor mediated vasoconstriction. An alpha-2 adrenoreceptor mediated release of endothelium-derived relaxing factor was demonstrated in pulmonary arteries from adult pigs but not in those from immature pigs. Arteries from immature pigs were less responsive to relaxation induced by nitric oxide and hypoxia but not by sodium nitroprusside. Bronchial rings from immature pigs produced greater force (normalised to wet weight) in response to acetylcholine or potassium chloride than did rings from adult pigs, although the concentration of acetycholine required to produced half-maximal response (EC50) was similar. Rings from newborn pigs were more sensitive to the bronchodilator ketamine than those from adult pigs, as manifested by a shift in EC50. The relaxant action of ketamine on tracheal smooth muscle was shown to be due to an inhibitory effect on excitation of the postsynaptic nicotinic receptors of the intramural parasympathetic ganglion and a direct effect on the smooth muscle cell. Nonadrenergic noncholinergic innervation was shown to be present from birth. Hypoxic bronchodilation was seen in bronchial rings from all ages. In conclusion, this study demonstrates age-related changes in the in vitro responsiveness of both pulmonary vascular and airway smooth muscle to contractile and relaxant agonists, responses depending not only upon the agonist used to elicit contraction or relaxation, but also upon the age of the animal studied.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available