title: Potassium chloride- and norepinephrine-induced contractile responses in rabbit pulmonary blood vessels.
abstract: Responses to KCl and norepinephrine (NE) were examined with ring segments of right extrapulmonary artery, intrapulmonary artery and intrapulmonary vein isolated from rabbit lung. From concentration-response curves to KCl, optimal applied loads were determined to be 5 g for right extrapulmonary artery and intrapulmonary artery and 500 mg for intrapulmonary vein. Both individual and cumulative concentration-response curves to KCI and NE were performed. All gave reproducible results; however, tissues were more sensitive to cumulative addition of either contractile agent. Of three successive cumulative NE concentration-response curves, second and third curves were most reproducible in relation to both sensitivity to NE and maximal force development. Cumulative NE concentration-response curves also exhibited a triphasic pattern, consisting of an initial contractile response (10(-10) to 10(-6) M NE) followed by relaxation or reversal of contractile force development (10(-6) to 10(-4) M NE), then a second contractile response at concentrations of NE greater than 10(-4) M. This response pattern was most prominent in intrapulmonary vessels and was absent in rabbit aorta.
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008168:Lung / Q000098:blood supply*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D009928:Organ Specificity; D011189:Potassium Chloride / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000187:drug effects; D011667:Pulmonary Veins / Q000187:drug effects; D011817:Rabbits; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D011189:Potassium Chloride; D009638:Norepinephrine