ISSN:
1440-1681
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
1. This study has pharmacologically characterized endothelin (ET) receptor subtype(s) mediating contraction and enhancement of adrenergic contraction in guinea-pig pulmonary artery. Isometric tension of the isolated endothelium-denuded ring preparations was measured in the presence of indomethacin (10−5 mol/L) and NG-nitro-L-arginine methyl ester (l-NAME; 3X10−4 mol/L) to exclude a mechanism via endothelium, cyclo-oxygenase-generated eicosanoids and nitric oxide.2. In the additional presence of tetrodotoxin (TTX; 3X10−7 mol/L), ET-1 (10−11-10−7 mol/L) concentration-dependently contracted the preparations. The rank order of potency to contract the preparations among ET receptor agonists was ET-1, sarafotoxin (STX) 6b〉ET-3〉IRL 1620, STX 6c. BQ-123 (7X10−7-7X10−6 mol/L) concentration-dependently shifted the concentration-contraction curve for ET-1 to the right in a parallel manner. Pretreatment with STX 6c (3X10−7 mol/L for 30 min) did not significantly desensitize contractions to ET-1, ET-3 or IRL 1620 (P〉0.05; t-test, 10 d. f.).3. ET-1 (10−10-10−9 mol/L) and STX 6b (10−9-10−8 mol/L) significantly enhanced the electrical field stimulation-induced contraction in a BQ-123-sensitive manner (P〈0.05; t-test, 24–38 d.f.), while ET-3 (10−11-10−8 mol/L) and STX 6c (10−11-10−7 mol/L) did not affect contractions. ET-1 (10−11 mol/L) significantly enhanced contractions to exogenous nor-adrenaline in the presence of TTX (3X10−7 mol/L) (P〈0.05; t-test, 16 d.f.).4. These data indicate that the BQ-123-sensitive ETA receptor mediates both contraction and enhancement of adrenergic contractions in the guinea-pig pulmonary artery.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1440-1681.1996.tb02745.x
Permalink