Sample tracings showing the effect of different neurotransmitters on the h-current; responses to hyperpolarizations to −130 mV from a holding potential of −40 mV; perforated patches, 37°C.

<p>The external saline included TTX, 4AP, TEA and Ba2+. A: Effects of the D2 agonist quinpirole (30 µM) and of the D2 antagonist sulpiride (20 µM); note that in the presence of the antagonist the response is greater than controls. B: Effect of 5-HT (100 µM). C: Effect of NA (100 µM). D: Time constant of the development of the effects of quinpirole and 5-HT.