Structure and function of beta3-adrenergic receptors.

Beta-adrenergic receptors have been subdivided into three types: beta1-, beta2- and beta3-adrenergic receptors. beta1-adrenergic receptors are predominant in the heart, beta2-adrenergic receptors--in the respiratory system, and beta3-adrenergic receptors--in the adipose tissues. However, since 1989, when beta3-adrenergic receptor was cloned, numerous biochemical and functional studies have confirmed its presence in various species and tissues, including the heart. Unlike beta1- and beta2-adrenergic receptors, it has been shown that beta3-adrenergic receptors possess the cardiodepressant effects in human ventricles, what did not fit to its stimulatory properties of adenylyl cyclase in other tissues. In this regard, the role of beta3-adrenergic receptors in the regulation of cardiac function may be of great importance in pathological conditions and remains undetermined, so far. In this review brief characterization of beta3-adrenergic receptors, concerning their structure, function and possible pathophysiological role is provided.