TY - JOUR T1 - Protein kinase C-mediated inhibition of recombinant T-type Ca <sub>V</sub> 3.2 channels by neurokinin 1 receptors JF - Molecular Pharmacology JO - Mol Pharmacol DO - 10.1124/mol.109.058727 SP - mol.109.058727 AU - Azahel Rangel AU - Sergio Sanchez-Armass AU - Ulises Meza Y1 - 2009/10/05 UR - http://molpharm.aspetjournals.org/content/early/2009/10/05/mol.109.058727.abstract N2 - The voltage-activated T-type calcium channel (CaV3.2) and the G protein-coupled neurokinin 1 (NK1) receptor are expressed in peripheral tissues and in central neurons where they participate in diverse physiological processes including neurogenic inflammation and nociception. In the present report, we demonstrate that recombinant CaV3.2 channels are reversibly inhibited by NK1 receptors when both proteins are transiently coexpressed in human embryonic kidney (HEK293) cells. We found that the voltage-dependent macroscopic properties of CaV3.2 currents were unaffected during NK1 receptor-mediated inhibition. However, inhibition was attenuated in cells coexpressing either the dominant-negative Gαq Q209L/D277N or the regulator of G protein signaling proteins 2 (RGS2) and 3T (RGS3T) which are effective antagonist of Gαq/11. By contrast, inhibition was unaffected in cells coexpressing human rod transducin (Gαt), which buffers Gβγ. Channel inhibition was blocked by U73122 and bisindolylmaleimide I, selective inhibitors of phospholipase Cβ and protein kinase C (PKC), respectively. Inhibition was occluded by application of the PKC activator phorbol-12-myristate-13-acetate (PMA). Altogether, these data indicate that NK1 receptors inhibit CaV3.2 channels through a voltage-independent signaling pathway that involves Gαq/11, phospholipase Cβ and PKC. Our results provide novel evidence regarding the mechanisms underlying T-type calcium channel modulation by G protein-coupled receptors. Functional coupling between CaV3.2 channels and NK1 receptors may be relevant in neurogenic inflammation, neuronal rhythmogenesis, nociception, and other physiological processes.The American Society for Pharmacology and Experimental Therapeutics ER -