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XB-ART-36070
J Cell Physiol 2008 Jan 01;2141:84-95. doi: 10.1002/jcp.21169.
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Modulation of the heteromeric Kir4.1-Kir5.1 channel by multiple neurotransmitters via Galphaq-coupled receptors.

Rojas A , Su J , Yang L , Lee M , Cui N , Zhang X , Fountain D , Jiang C .


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The heteromeric Kir4.1-Kir5.1 channel is a candidate sensing molecule for central CO(2) chemoreception. Since central CO(2) chemoreception is subject to neural modulations, we performed studies to test the hypothesis that the Kir4.1-Kir5.1 channel is modulated by the neurotransmitters critical for respiratory control, including serotonin (5-HT), substance-P (SP), and thyrotropin releasing hormone (TRH). The heteromeric Kir4.1-Kir5.1 channel was strongly inhibited by SP, TRH, and 5-HT when expressed in Xenopus oocytes, whereas these neurotransmitters had no effect on the homomeric Kir4.1 channel. Such an inhibition was dose-dependent and relied on specific G(alphaq)-protein-coupled receptors and protein kinase C (PKC). No direct interaction of the channel with G-proteins was found. Channel sensitivity to CO(2)/pH was not compromised with the inhibition by these neurotransmitters, as the channel remained to be inhibited by acidic pH following an exposure to the neurotransmitters. The firing rate of CO(2)-sensitive brainstem neurons cultured in microelectrode arrays was augmented by SP or a 5-HT2A receptor agonist, which was blocked by PKC inhibitors suggesting that PKC underscores the inhibitory effect of SP and 5-HT in cultured brainstem neurons as well. Immunostaining showed that both Kir4.1 and Kir5.1 proteins were co-localized in the cultured brainstem neurons. These results therefore indicate that the heteromeric Kir4.1-Kir5.1 channel is modulated by the neurotransmitters critical for respiratory control, suggesting a novel neuromodulatory mechanism for the chemosensitivity of brainstem neurons to elevated PCO(2) and acidic pH.

???displayArticle.pubmedLink??? 17559083
???displayArticle.pmcLink??? PMC4132838
???displayArticle.link??? J Cell Physiol
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Species referenced: Xenopus laevis
Genes referenced: kcnj10 kcnj16 trh

References [+] :
Bajic, Two different inward rectifier K+ channels are effectors for transmitter-induced slow excitation in brain neurons. 2002, Pubmed