5-HT1 receptor agonists reduce the Ca+ component of sensory neuron action potentials.

Serotonin (5-HT) agonists, selective for 5-HT1, 5-HT2 or 5-HT3 receptor subtypes, were tested for their ability to mimic 5-HT in narrowing the tetraethylammonium-induced calcium-dependent plateau of action potentials recorded from frog sensory neurons. 5-Carboxamidotryptamine, 5-HT, alpha-methyl 5-HT and 5-methoxy-tryptamine possessed full agonist activity, with EC50S of 19 nM, 210 nM, 3.7 microM and 1.7 microM, respectively. 2-Methyl 5-HT was inactive. This agonist profile indicates that the calcium-dependent plateau in these sensory somata is modulated by a 5-HT1-like receptor.