Serotonergic responses in rabbit ophthalmic artery: a pharmacological characterization.
The contractile effect of serotonin (5-HT) on rabbit ophthalmic artery was studied. In a solution containing 20 mM K+ 5-HT induced a biphasic dose-response curve (DRC) in intact arteries. At normal extracellular K+ concentration ([K+]o), only high concentrations of 5-HT (greater than or equal to 1 microM) were able to induce contraction. In endothelium-denuded arteries 5-HT induced a DRC at normal [K+]o, which resembled that in intact arteries at 20 mM [K+]o. The high-potency portion of the 5-HT DRC was inhibited only by metitepine, whereas the low-potency portion was blocked by metitepine, methysergide, spiperone, and ketanserin, indicating that in this preparation the 5-HT1 receptor subtypes are more sensitive to 5-HT than the 5-HT2 receptor subtypes. Cyanopindolol had no effect on 5-HT-induced contraction. 8-Hydroxy-2-(di-n-propylamino)tetralin gave a contraction at high concentrations (greater than or equal to 0.1 microM), which was not blocked by cyanopindolol. The contractile response to 5-methoxytryptamine was similar to that for 5-HT. The results indicate that the 5-HT1 receptors of the ophthalmic artery belong either to 1C or 1D subtypes. 2-Methylserotonin, an agonist for 5-HT3 receptor, had no contractile effect on rabbit ophthalmic artery. The effect of prior exposure to 5-HT on norepinephrine (NE)-induced contraction was also studied. In intact arteries prior exposure to a low 5-HT concentration (10 nM) induced attenuation and prior exposure to a high 5-HT concentration (1 microM) gave potentiation of the NE-induced contraction.(ABSTRACT TRUNCATED AT 250 WORDS)
Zschauer
A
A
Department of Anatomy, University of Helsinki, Finland.
van Breemen
C
C
Uusitalo
H
H
D008735:5-Methoxytryptamine / Q000494:pharmacology; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology; D008784:Methysergide / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D009880:Ophthalmic Artery / Q000187:drug effects / Q000503:physiopathology*; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
D012702:Serotonin Antagonists; D013764:Tetrahydronaphthalenes; D012701:Serotonin; D008735:5-Methoxytryptamine; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D011188:Potassium; D009638:Norepinephrine; D008784:Methysergide