Aminophylline preferentially inhibits chloroethylclonidine-insensitive alpha-adrenoceptor-mediated contractions in rat aorta.
1. In rat thoracic aortae, contractions induced by methoxamine were inhibited by chloroethylclonidine, whereas oxymetazoline-induced contractions, which were more dependent on Ca(2+)-entry, were insensitive to chloroethylclonidine. 2. Aminophylline inhibited the contractions and 45Ca(2+)-uptake induced by both methoxamine and oxymetazoline. However, oxymetazoline-induced contractions were more sensitive to inhibition by aminophylline and D600. 3. Thus, the partial selectivity of aminophylline for the chloroethylclonidine-resistant, highly dependent on extracellular Ca2+, oxymetazoline-mediated responses may be explained by a preferential inhibition of agonist-induced Ca2+ entry as compared to inhibition of other transduction pathways.
Duarte
J
J
Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain.
Pérez-Vizcaíno
F
F
Zarzuelo
A
A
Jiménez
J
J
Tamargo
J
J
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000628:Aminophylline / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002132:Calcium Radioisotopes; D003000:Clonidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D005711:Gallopamil / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008729:Methoxamine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D010109:Oxymetazoline / Q000037:antagonists & inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D002132:Calcium Radioisotopes; D011942:Receptors, Adrenergic, alpha; D000628:Aminophylline; D005711:Gallopamil; C051731:chlorethylclonidine; D010109:Oxymetazoline; D008729:Methoxamine; D003000:Clonidine; D002118:Calcium