Amplifying effect of serotonin on contractile responses in rat aorta and depletion of intracellular Ca-stores

Abstract

1. 1. Serotonin, 1 μM, induces a contractile response in isolated rat aorta in the presence or absence of extracellular Ca. 2. 2. In Ca-free media, the fast phasic contraction is lower in magnitude and further addition of serotonin evokes no response. 3. 3. Recovery of the contractile response in Ca-free medium is obtained by a 40 min incubation in Ca-containing solution. 4. 4. In Ca, Mg-free medium, the response to serotonin is significantly higher than that obtained in the presence of Mg. 5. 5. An amplifying effect of serotonin on the contractile responses induced by serotonin itself or by noradrenaline was observed in Ca-containing but not in Ca-free solution.