Obesity is one of the major risk factors for asthma. Previous studies have demonstrated that free fatty acid levels are elevated in the plasma of obese individuals. Medium- and long-chain free fatty acids act as endogenous ligands for the free fatty acid receptors FFAR1/GPR40 and FFAR4/GPR120, which couple to Gq proteins. We investigated whether FFAR1 and FFAR4 are expressed on airway smooth muscle and whether they activate Gq-coupled signaling and modulate airway smooth muscle tone. We detected the protein expression of FFAR1 and FFAR4 in freshly dissected native human and guinea pig airway smooth muscle and cultured human airway smooth muscle (HASM) cells by immunoblotting and immunohistochemistry. The long-chain free fatty acids (oleic acid and linoleic acid) and GW9508 (FFAR1/FFAR4 dual agonist) dose-dependently stimulated transient intracellular Ca(2+) concentration ([Ca(2+)]i) increases and inositol phosphate synthesis in HASM cells. Downregulation of FFAR1 or FFAR4 in HASM cells by small interfering RNA led to a significant inhibition of the long-chain free fatty acids-induced transient [Ca(2+)]i increases. Oleic acid, linoleic acid, or GW9508 stimulated stress fiber formation in HASM cells, potentiated acetylcholine-contracted guinea pig tracheal rings, and attenuated the relaxant effect of isoproterenol after an acetylcholine-induced contraction. In contrast, TUG-891 (FFAR4 agonist) did not induce the stress fiber formation or potentiate acetylcholine-induced contraction. These results suggest that FFAR1 is the functionally dominant free fatty acid receptor in both human and guinea pig airway smooth muscle. The free fatty acid sensors expressed on airway smooth muscle could be an important modulator of airway smooth muscle tone.
Our meta-analysis suggests that the McGrath is superior to the Macintosh in terms of glottic visualization (GRADE: moderate). However, it significantly extends intubation time (GRADE: very low) and its success rate (GRADE: very low) for tracheal intubation is not excellent. TSA suggests that further studies are necessary to confirm the results of intubation time.
SummaryThe Pentax Airway Scope â is a single-use optical videolaryngoscope designed to assist with difficult tracheal intubation. We systematically reviewed the efficacy of the Pentax Airway Scope with that of a conventional laryngoscope for tracheal intubation in adults with 'normal' and 'difficult' airways. We included 17 randomised controlled trials with a total of 1801 participants. We used the DerSimonian and Laird random-effects model to calculate pooled relative risk or weighted mean differences. The relative risk (95%
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