A role for Na+/H+ exchange in contraction of guinea pig airways by endothelin-1 in vitro.
Endothelin-1-induced contractions of guinea pig tracheal and bronchial strips were dose-dependently attenuated by the amiloride analogues 5-(N-ethyl-N-isopropyl)amiloride (EIPA, 1-10 microM) and 5-(N,N-hexamethylene)amiloride (HMA, 1-10 microM). The calculated Ki values for EIPA and HMA were 0.11 +/- 0.02 microM and 0.06 +/- 0.02 microM in the trachea, and 0.28 +/- 0.11 microM and 0.70 +/- 0.25 microM in the bronchus, respectively. These values are in the same order of magnitude as those reported for inhibition of the Na+/H+ exchange in cells. Amiloride (1-10 microM) was ineffective. These data suggest that activation of the Na+/H+ exchange by ET-1 may be involved in mediating its myotropic action in guinea pig airway smooth muscle.
Battistini
B
B
Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, (PQ), Canada.
Filep
J G
JG
Cragoe
E J
EJ
Fournier
A
A
Sirois
P
P
D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D016084:Bronchoconstriction / Q000187:drug effects*; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D016232:Endothelins / Q000494:pharmacology*; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D012964:Sodium / Q000502:physiology; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D016232:Endothelins; D017923:Sodium-Hydrogen Exchangers; C057360:5-(N,N-hexamethylene)amiloride; C039465:5-dimethylamiloride; D000584:Amiloride; D012964:Sodium