Alpha(1)-adrenoceptor-mediated depolarization and beta-mediated hyperpolarization in cultured rat dorsal root ganglion neurones.

The mechanism of sympathetic - sensory coupling after nerve injury is still not well understood. We have studied the changes in resting potential and excitability of sensory neurones induced by adrenergic stimulation, using whole-cell and perforated-patch recordings in cultured dorsal root ganglion neurones from normal rats. Adrenaline (1-100 microM) depolarized 18 of 39 neurones (46%) and hyperpolarized seven neurones (18%); excitability was increased and decreased, respectively. Stimulating the neurones with 10 microM phenylephrine (alpha(1)-agonist) induced depolarization and increased excitability, while 10 microM isoprenaline (beta-agonist) induced hyperpolarization and reduced excitability. We conclude that alpha(1)- and beta-receptors have opposing effects on membrane potential and excitability in cultured dorsal root ganglion neurones, and the differing effects of adrenaline can be explained by different degrees of expression of each receptor type.