A Mechanism for Nerve Cell Excitation by Norepinephrine via Alpha-1 Adrenoceptors: Inhibition of Potassium M-Current

作者：Filippov Alexander K; Brown David A^*

来源：Cellular and Molecular Neurobiology, 2013, 33(1): 1-4.

DOI：10.1007/s10571-012-9870-y

• alpha 1 Adrenoceptors
• Norepinephrine
• Phenylephrine
• M-current
• Potassium current
• Sympathetic neurons

Some of the excitatory effects of norepinephrine on central neurons are mediated by alpha-1 (alpha 1) adrenoceptors. These receptors are coupled to the Gq family of G proteins, and hence stimulate hydrolysis of the membrane phospholipid phosphatidylinositol-4,5-bisphosphate. Other receptors of this type can excite neurons by inhibiting the subthreshold voltage-gated potassium M-current. We tested this possibility using rat sympathetic neurons transformed to express alpha 1a receptors. The alpha 1 agonist phenylephrine strongly inhibited the M-current recorded under voltage-clamp by 72 +/- A 11 % (n = 4) and in an unclamped neuron dramatically increased the number of action potentials produced by a 2 s depolarizing current step from 2 to 40, without effect on control neurons devoid of alpha 1 receptors. We suggest that this might be a potential cause of the increased excitability produced by norepinephrine in some central neurons.

• 出版日期2013-1