Serotonin receptor‐mediated vasorelaxation occurs primarily through 5‐HT4 activation in bovine lateral saphenous vein

Abstract To better understand mechanisms of serotonin‐ (5‐HT) mediated vasorelaxation, isolated lateral saphenous veins from cattle were assessed for vasoactivity using myography in response to increasing concentrations of 5‐HT or selective 5‐HT receptor agonists. Vessels were pre‐contracted with 1 × 10−4 M phenylephrine and exposed to increasing concentrations of 5‐HT or 5‐HT receptor agonists that were selective for 5‐HT1B, 5‐HT2B, 5‐HT4, and 5‐HT7. Vasoactive response data were normalized as a percentage of the maximum contractile response induced by the phenylephrine pre‐contraction. At 1 × 10−7 M 5‐HT, a relaxation was observed with an 88.7% decrease (p