Effects of 5-hydroxytryptamine and ergotamine on human superficial temporal artery

Isometric tension was recorded in ring preparations of human superficial temporal arteries contracted by noradrenaline (NA), 5-hydroxytryptamine (5-HT), and ergotamine. In contrast to NA and 5-HT, ergotamine induced long-lasting contractions refractive to additional stimulations and resistant to repeated wash-out. When tested against 5-HT, ergotamine acted as a non-competitive antagonist. When repeating the 5-HT stimulations (4.7 x 10(-5) M) the contractile response decreased indicating tachyphylaxis to this agent. As ergotamine revealed both a vasoconstrictive and a 5-HT-blocking activity, the beneficial effect in migraine may be by an interference during both the vasoconstrictory and vasodilatory phases.