Faculty Opinions recommendation of Targeting the restricted α-subunit repertoire of airway smooth muscle GABAA receptors augments airway smooth muscle relaxation.

The prevalence of asthma has taken on pandemic proportions. Since this disease predisposes patients to severe acute airway constriction, novel mechanisms capable of promoting airway smooth muscle relaxation would be clinically valuable. We have recently demonstrated that activation of endogenous airway smooth muscle GABA(A) receptors potentiates β-adrenoceptor-mediated relaxation, and molecular analysis of airway smooth muscle reveals that the α-subunit component of these GABA(A) receptors is limited to the α(4)- and α(5)-subunits. We questioned whether ligands with selective affinity for these GABA(A) receptors could promote relaxation of airway smooth muscle. RT-PCR analysis of GABA(A) receptor subunits was performed on RNA isolated by laser capture microdissection from human and guinea pig airway smooth muscle. Membrane potential and chloride-mediated current were measured in response to GABA(A) subunit-selective agonists in cultured human airway smooth muscle cells. Functional relaxation of precontracted guinea pig tracheal rings was assessed in the absence and presence of the α(4)-subunit-selective GABA(A) receptor agonists: gaboxadol, taurine, and a novel 8-methoxy imidazobenzodiazepine (CM-D-45). Only messenger RNA encoding the α(4)- and α(5)-GABA(A) receptor subunits was identified in RNA isolated by laser capture dissection from guinea pig and human airway smooth muscle tissues. Activation of airway smooth muscle GABA(A) receptors with agonists selective for these subunits resulted in appropriate membrane potential changes and chloride currents and promoted relaxation of airway smooth muscle. In conclusion, selective subunit targeting of endogenous airway smooth muscle-specific GABA(A) receptors may represent a novel therapeutic option for patients in severe bronchospasm. PMID: 21949156 Funding information This work was supported by: NHLBI NIH HHS, United States Grant ID: R01 HL077726 NIGMS NIH HHS, United States Grant ID: GM093137 NIGMS NIH HHS, United States Grant ID: GM065281 NIGMS NIH HHS, United States Grant ID: K08 GM093137 NHLBI NIH HHS, United States Grant ID: T35 HL007616 NIMH NIH HHS, United States Grant ID: R01 MH096463 NINDS NIH HHS, United States Grant ID: R01 NS076517 More Less keyboard_arrow_down

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