title: Thromboxane-mediated alveolar responses to acute obstruction of the pulmonary vasculature.
abstract: To investigate the mechanisms responsible for the accelerated radioaerosol transalveolar clearance rates caused by acute balloon occlusion of the pulmonary arterial tree in dogs, the effects of vagal tone (n = 5) and prostaglandins (n = 21) including thromboxane were evaluated. In 15 animals, serial pulmonary arterial and aortic blood samples were acquired to evaluate pertinent metabolic products. Balloon occlusion of a localized arterial territory caused significant acceleration of technetium-99m diethylenetriamine pentaacetic acid (Tc-99m DTPA) clearance in the zone immediately distal to the occlusion (baseline clearance half-time 23.1 +/- 0/7 min versus 19.3 +/- 0.4 min, mean +/- SEM, p < 0.05). Vagotomy had no effect on occlusion-accelerated clearance. However, significant (p < 0.05) normalization did occur in the presence of indomethacin (21.9 +/- 0.4 min) and meclofenamic acid (20.4 +/- 0.5 min). Plasma values of thromboxane rose dramatically (pulmonary blood baseline 119 pg/ml to > 40,000 pg/ml) and transiently immediately after pulmonary vascular occlusion, and this rise was blunted significantly (peak pulmonary thromboxane B2 [TXB2] concentration = 668 pg/ml, p < 0.05) by meclofenamic acid. Significant normalization of local DTPA clearance rates also occurred in the presence of a thromboxane receptor blocker (n = 4), even when blood levels of thromboxane were elevated. Changes in transalveolar DTPA clearance rates after balloon occlusion of pulmonary arteries seem to a significant extent to be thromboxane-mediated.
authors.affiliation: Department of Radiology, College of Physicians and Surgeons, Columbia-Presbyterian Medical Center, New York, New York 10032, USA.
authors.forename: A
authors.initials: A
authors.lastname: Mitra
authors.forename: S J
authors.initials: SJ
authors.lastname: Feinmark
authors.forename: P O
authors.initials: PO
authors.lastname: Alderson
mesh_terms: D000818:Animals; D001157:Arterial Occlusive Diseases / Q000503:physiopathology*; D002404:Catheterization; D004285:Dogs; D008469:Meclofenamic Acid / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000503:physiopathology*; D011651:Pulmonary Artery; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics; D013928:Thromboxane A2 / Q000502:physiology; D013929:Thromboxane B2 / Q000502:physiology; D013931:Thromboxanes / Q000502:physiology*
chemical_list: D019275:Radiopharmaceuticals; D013931:Thromboxanes; D008469:Meclofenamic Acid; D013929:Thromboxane B2; D013928:Thromboxane A2; D016284:Technetium Tc 99m Pentetate