Drug-induced changes of vasomotor tone in isolated human segmental pulmonary arteries
Boe, J.
European Journal of Respiratory Diseases. Supplement 112: 1-45
1981
ISSN/ISBN: 0106-4347 PMID: 6114873 Document Number: 182470
Spirally cut human pulmonary segmental artery strips taken from patients undergoing thoracic surgery are a convenient model to study vasomotor changes due to chemical mediators. None of the patients showed preoperative signs of pulmonary hypertension, and no statistically significant difference could be demonstrated for contractions induced with prostaglandin and angiotensin II. No statistically significant difference could be observed between the contractions elicited with NE and epinephrine or between carbachol and acetylcholine and no significant difference for threshold doses or ED50 were found between histamine, PGF2.alpha., acetylcholine or carbachol. As the isolated pulmonary arteries had no resting tone, relaxation was investigated after an induced increase of tone with contractory substances. No statistically significant difference was found between the relaxing potency of the 2 drugs. No relaxation could be induced with the selective .beta.2-stimulants salbutamol or terbutaline, or with acetylcholine or carbachol. PGE1 showed a total relaxation in 11 of 21 specimens of PGF2.alpha.-contracted vessels. A slight relaxation was induced by bradykinin. With the aid of specific antagonists it was possible in the isolated human pulmonary arteries to postulate the presence of adrenergic .alpha.- and .beta.1-receptors, muscarinic parasympathetic receptors, serotonergic receptors, histamine H1- and H2-receptors and angiotensin II-receptors. The presence of receptors for PGF2.alpha. and PGE1 is suggested. PGF2.alpha. and histamine contracted and PGE1 relaxed pulmonary segmental artery specimens taken at autopsy from a patient with primary pulmonary hypertension, indicating that vasomotor changes due to chemical mediators may appear even in morphologically changed vessels. Additional studies of pulmonary vessels from patients with pulmonary hypertension with the described technique are desirable. Results obtained from in vitro studies can form a better basis for extended in vivo studies in human health and disease.