[A comparison of the effects of serotonin, 2-(2-aminoethyl)quinoline (D-1997) and sumatriptan on the external carotid blood flow in the dog].

The quinoline derivative, 2-(2-aminoethyl)-quinoline (D-1997) has been shown to mimic the contractile effects induced by serotonin (5-hydroxytryptamine; 5-HT) in the saphenous vein and basilar artery of the dog. Inasmuch as the receptor mechanisms mediating the above effects are similar to those involved in 5-HT-induced vasoconstriction of the canine common carotid circulation, the present study was set out to analyze the haemodynamic profile of D-1997 in the canine external carotid vascular bed. The effects of D-1997 were compared with those produced by 5-HT and the antimigraine drug, sumatriptan. One-min intracarotid (i.c.) infusions of D-1997 (10, 30, 100, 300 and 1000 micrograms/min), 5-HT (0.3, 1, 3, 10, 30 and 100 micrograms/min) and sumatriptan (3, 10, 30 and 100 micrograms/min) elicited dose-dependent decreases in external carotid blood flow (ECBF); since the infusions of agonists did not modify arterial blood pressure, they produced dose-dependent increases in external carotid resistance (ECR). The vasoconstrictor responses to D-1997 and 5-HT were of short duration (up to 10 min) whilst those to sumatriptan were longer lasting (up to 40 min). In addition, the effects induced by the agonists in the external carotid bed did not affect basal resistance in the contralateral common carotid, thereby suggesting a local effect by D-1997. The rank order of agonist potency was 5-HT > sumatriptan > D-1997; however, the order of agonist efficacy, represented as the maximum response obtained with the highest dose, displayed a different pattern, namely, D-1997 > or = sumatriptan > 5-HT.(ABSTRACT TRUNCATED AT 250 WORDS)