title: Discrimination between phenylephrine-triggered contractile events by atrial natriuretic factor in rat aorta.
abstract: The effects of atrial natriuretic factor (ANF) on contractile events triggered by phenylephrine (PE) were investigated in rat aorta. Isometric contraction of endothelium-free rat aorta rings was recorded in Ca2+-free medium containing 1 mM EGTA. PE (1 microM) induced a phasic contraction and a sustained contraction following addition of Ca2+ (2.5 mM) to the medium. The phasic contraction was due to intracellular Ca2+ release whereas the sustained one was dependent on extracellular Ca2+ influx. ANF (1-3 nM) and prazosin (3-10 nM) both reduced the two types of contraction. However, during the sustained contraction, a rhythmic activity was observed when ANF, but not prazosin, was used as an inhibitory agent. The calcium antagonist diltiazem (0.1-1 microM) abolished this rhythmic activity, which was attributed to a Ca2+ influx through potential-dependent channels. The results indicate that ANF, unlike prazosin, may discriminate between PE-triggered contractile events in the rat aorta.
authors: IHB Research Laboratories, ZA de Courtaboeuf, Les Ulis, France.
authors: M
authors: M
authors: Auguet
authors: S
authors: S
authors: Delaflotte
authors: P
authors: P
authors: Braquet
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002122:Calcium Chloride / Q000494:pharmacology; D004347:Drug Interactions; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010656:Phenylephrine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: C472610:atrial natriuretic peptide, rat; D010656:Phenylephrine; D009320:Atrial Natriuretic Factor; D002122:Calcium Chloride