Inflammatory mediators mediate airway smooth muscle contraction through a G protein-coupled receptor-transmembrane protein 16A-voltage-dependent Ca2+ channel axis and contribute to bronchial hyperresponsiveness in asthma.

BACKGROUND: Allergic inflammation has long been implicated in asthmatic hyperresponsiveness of airway smooth muscle (ASM), but its underlying mechanism remains incompletely understood. Serving as G protein-coupled receptor agonists, several inflammatory mediators can induce membrane depolarization, contract ASM, and augment cholinergic contractile response. We hypothesized that the signal cascade integrating on membrane depolarization by the mediators might involve asthmatic hyperresponsiveness. OBJECTIVE: We sought to investigate the signaling transduction of inflammatory mediators in ASM contraction and assess its contribution in the genesis of hyperresponsiveness. METHODS: We assessed the capacity of inflammatory mediators to induce depolarization currents by electrophysiological analysis. We analyzed the phenotypes of transmembrane protein 16A (TMEM16A) knockout mice, applied pharmacological reagents, and measured the Ca2+ signal during ASM contraction. To study the role of the depolarization signaling in asthmatic hyperresponsiveness, we measured the synergistic contraction by methacholine and inflammatory mediators both ex vivo and in an ovalbumin-induced mouse model. RESULTS: Inflammatory mediators, such as 5-hydroxytryptamin, histamine, U46619, and leukotriene D4, are capable of inducing Ca2+-activated Cl- currents in ASM cells, and these currents are mediated by TMEM16A. A combination of multiple analysis revealed that a G protein-coupled receptor-TMEM16A-voltage-dependent Ca2+ channel signaling axis was required for ASM contraction induced by inflammatory mediators. Block of TMEM16A activity may significantly inhibit the synergistic contraction of acetylcholine and the mediators and hence reduces hypersensitivity. CONCLUSIONS: A G protein-coupled receptor-TMEM16A-voltage-dependent Ca2+ channel axis contributes to inflammatory mediator-induced ASM contraction and synergistically activated TMEM16A by allergic inflammatory mediators with cholinergic stimuli.

CPI-17-mediated contraction of vascular smooth muscle is essential for the development of hypertension in obese mice.

Several factors have been implicated in obesity-related hypertension, but the genesis of the hypertension is largely unknown. In this study, we found a significantly upregulated expression of CPI-17 (C-kinase-potentiated protein phosphatase 1 inhibitor of 17 kDa) and protein kinase C (PKC) isoforms in the vascular smooth muscles of high-fat diet (HFD)-fed obese mice. The obese wild-type mice showed a significant elevation of blood pressure and enhanced calcium-sensitized contraction of vascular smooth muscles. However, the obese CPI-17-deficient mice showed a normotensive blood pressure, and the calcium-sensitized contraction was consistently reduced. In addition, the mutant muscle displayed an abolished responsive force to a PKC activator and a 30%-50% reduction in both the initial peak force and sustained force in response to various G protein-coupled receptor (GPCR) agonists. Our observations showed that CPI-17-mediated calcium sensitization is mediated through a GPCR/PKC/CPI-17/MLCP/RLC signaling pathway. We therefore propose that the upregulation of CPI-17-mediated calcium-sensitized vasocontraction by obesity contributes to the development of obesity-related hypertension.

[The protective effect of Rhadiola Astragalus Codonopsis compound on myocardium in early stage of severe burn at plateau in rats].

OBJECTIVE: To investigate the severity of early myocardial injury in rats with 30% full thickness burn at plateau and the protective effects of Rhadiola Astragalus Codonopsis Compound (RACC) on the rat myocardial injury. METHODS: One hundred and four Wistar rats with 30% full thickness burn were randomly divided into RACC application (R, n = 48) and scalding group 1 (S, n = 48), and another 8 healthy Wistar rats as control group 2 (C, n = 8). Four ml of RACC was garaged into the rat stomach in R and 4 ml isotonic saline in S groups respectively, but no treatment in C group. Blood samples from the aorta were harvested in 3, 6, 12, 24, 48 and 72 postburn hours (PBH) for blood gas analysis and for the determination of the changes in myocardial enzymes. Rat heart was harvested for pathomorphological examination. RESULTS: The rat myocardial tissue injury in R and S groups was obvious at 3 PBH and ameliorated gradually thereafter, up to the degree in C group at 72 PBH. The serum levels of myocardial enzymes in R and S groups were significantly higher than those in C group (P < 0.01). Whereas the enzymes in R group were much lower than those in S group (P < 0.01). It was indicated by blood gas analysis that the pH in R and S groups was lower than that in C group (P < 0.05), while that in R group at 12 - 24 PBH was higher than that in S group (P < 0.05). In addition, the base excess in R and S groups was lower than that in C group (P < 0.01), while that in R group at 6 PBH was higher than that in S group (P < 0.05 approximately 0.01). The PaCO2 in R and S groups was evidently lower than that in C group (P < 0.05 approximately 0.01), while that in R group at 48 PBH was no different to that in C group (35.70 +/- 4.23 mmHg vs 37.50 +/- 6.53 mmHg, P > 0.05). The PaO2 in R and S groups at 3 approximately 24 PBH was higher than that in C group and decreased gradually (P > 0.05). There was no difference in SaO2 among 3 groups (P > 0.05). CONCLUSION: RACC exhibited beneficial to the protection of rat heart from myocardial injury at plateau induced by severe burn.