Functional interactions between neuronal AT1 and AT2 receptors.

Angiotensin II (Ang II), via the activation of the AT1 and AT2 receptors regulates electrophysiological responses of catecholaminergic neurons. This study was designed to determine if functional interactions between AT1 and AT2 receptors exist in a single neuron. Ang II caused two unique electrophysiological responses characteristic of receptor crosstalk. First, Ang II elicited an AT1 receptor-mediated decrease in I(K) followed by an AT2 receptor-mediated increase in I(K). Second, Ang II elicited an AT2 receptor-mediated increase in I(K) followed by an AT1 receptor-mediated decrease in I(K). AT1 and AT2 receptors were co-localized on the catecholaminergic neurons. These observations suggest, for the first time, the existence of a crosstalk between Ang II receptor subtypes that may be significant in the physiological activity of catecholaminergic neurons.