title: Cirazoline, an alpha 2-adrenoceptor antagonist in guinea-pig ileum.
abstract: Prejunctional effects of cirazoline have been investigated in guinea pig ileum. At high concentrations cirazoline has been shown to have antimuscarinic activity, pA2 5.25 +/- 0.29. At concentrations below those producing blockade of acetylcholine, cirazoline blocks the prejunctional alpha 2-adrenoceptor activity of clonidine, pA2 6.81 +/- 0.22, and alpha-methylnoradrenaline. Results are discussed in the light of controversial evidence for the activity of cirazoline on alpha-adrenoceptors.
mesh_terms: D000109:Acetylcholine / Q000037:antagonists & inhibitors; D000818:Animals; D003000:Clonidine / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000502:physiology*; D007093:Imidazoles / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D008771:Nordefrin / Q000037:antagonists & inhibitors; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*
chemical_list: D007093:Imidazoles; D011942:Receptors, Adrenergic, alpha; D003000:Clonidine; D000109:Acetylcholine; C014282:cirazoline; D008771:Nordefrin