Abrogation of thrombin-induced increase in pulmonary microvascular permeability in PAR-1 knockout mice.
We investigated the function of proteinase-activated receptor-1 (PAR-1) in the regulation of pulmonary microvascular permeability in response to thrombin challenge using PAR-1 knockout mice (-/-). Lungs were isolated and perfused with albumin (5 g/100 ml)-Krebs solution at constant flow (2 ml/min). Lung wet weight and pulmonary artery pressure (P(pa)) were continuously monitored. We determined the capillary filtration coefficient (K(fc)) and (125)I-labeled albumin (BSA) permeability-surface area product (PS) to assess changes in pulmonary microvessel permeability to liquid and albumin, respectively. Normal and PAR-1-null lung preparations received in the perfusate: 1) thrombin or 2) selective PAR-1 agonist peptide (TFLLRNPNDK-NH(2)). In control PAR-1 (+/+) mouse lungs, (125)I-albumin PS and K(fc) were significantly increased over baseline (by approximately 7- and 1.5-fold, respectively) within 20 min of alpha-thrombin (100 nM) challenge. PAR-1 agonist peptide (5 microM) gave similar results, whereas control peptide (5 microM; FTLLRNPNDK-NH(2)) was ineffective. At relatively high concentrations, thrombin (500 nM) or PAR-1 agonist peptide (10 microM) also induced increases in P(pa) and lung wet weight. All effects of thrombin (100 or 500 nM) or PAR-1 agonist peptide (5 or 10 microM) were prevented in PAR-1-null lung preparations. Baseline measures of microvessel permeability and P(pa) in the PAR-1-null preparations were indistinguishable from those in normal lungs. Moreover, PAR-1-null preparations gave normal vasoconstrictor response to thromboxane analog, U-46619 (100 nM). The results indicate that the PAR-1 receptor is critical in mediating the permeability-increasing and vasoconstrictor effects of thrombin in pulmonary microvessels.
Vogel
S M
SM
Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA. vogel@uic.edu
Gao
X
X
Mehta
D
D
Ye
R D
RD
John
T A
TA
Andrade-Gordon
P
P
Tiruppathi
C
C
Malik
A B
AB
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005838:Genotype; D066298:In Vitro Techniques; D008168:Lung / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018994:Myosin Light Chains / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011652:Pulmonary Circulation / Q000187:drug effects*; D012313:RNA / Q000235:genetics / Q000378:metabolism; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin / Q000235:genetics* / Q000502:physiology; D013917:Thrombin / Q000494:pharmacology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D018994:Myosin Light Chains; D009842:Oligopeptides; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; D014662:Vasoconstrictor Agents; D012313:RNA; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D013917:Thrombin