摘要:

&bgr;-Adrenergic agonists accelerate the clearance of alveolar fluid by increasing the expression and activity of epithelial solute transport proteins such as amiloride-sensitive epithelial Na+channels (ENaC) and Na,K-ATPases. Here we report that adenoviral-mediated overexpression of a human &bgr;2-adrenergic receptor (&bgr;2AR) cDNA increases &bgr;2AR mRNA, membrane-bound receptor protein expression, and receptor function (procaterol-induced cAMP production) in human lung epithelial cells (A549). Receptor overexpression was associated with increased catecholamine (procaterol)-responsive active Na+transport and increased abundance of Na,K-ATPases in the basolateral cell membrane. &bgr;2AR gene transfer to the alveolar epithelium of normal rats improved membrane-bound &bgr;2AR expression and function and increased levels of ENaC (&agr; subunit) abundance and Na,K-ATPases activity in apical and basolateral cell membrane fractions isolated from the peripheral lung, respectively. Alveolar fluid clearance (AFC), an index of active Na+transport, in &bgr;2AR overexpressing rats was up to 100% greater than sham-infected controls and rats infected with an adenovirus that expresses no cDNA. The addition of the &bgr;2AR-specific agonist procaterol to &bgr;2AR overexpressing lungs did not increase AFC further. AFC in &bgr;2AR overexpressing lungs from adrenalectomized or propranolol-treated rats revealed clearance rates that were the same or less than normal, untreated, sham-infected controls. These experiments indicate that alveolar &bgr;2AR overexpression improves &bgr;2AR function and maximally upregulates &bgr;-agonist–responsive active Na+transport by improving responsiveness to endogenous catecholamines. These studies suggest that upregulation of &bgr;2AR function may someday prove useful for the treatment of pulmonary edema.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

We investigated the role of stress-activated p38 MAP kinase (p38/SAPK-2) signaling in delayed preconditioning of the heart. Adult male out-bred ICR mice were treated with p38 activator, anisomycin (0.1 mg/kg IP), or vehicle (5% DMSO). Twenty-four hours later, hearts were perfused in Langendorff mode and subjected to 30 minutes of ischemia and 30 minutes of reperfusion. Improvement in postischemic recovery of end-diastolic pressure and reduction in infarct size was observed, which was abolished by SB203580, a specific p38 inhibitor, and pyrrolidinediethyldithiocarbamate (PDTC), the NF-&kgr;B inhibitor, but not by PD 98059, a specific inhibitor for MEK1 or 2. Transient increase in p38 phosphorylation was observed 15 minutes after anisomycin treatment which subsided by 30 minutes. Electrophoretic mobility shift assay demonstrated rapid activation of NF-&kgr;B DNA binding with anisomycin, peaking at 30 minutes. Western blot confirmed the accumulation of p50 and p65 in nuclear extracts after anisomycin treatment. Anisomycin-induced NF-&kgr;B DNA binding activity was inhibited by SB203580 and PDTC. Expression of inducible nitric oxide synthase (iNOS) mRNA, protein, and nitric oxide (NO) synthesis were enhanced in anisomycin-treated mice. SB203580 and PDTC blocked the increased expression of iNOS and increase in synthesis of NO. Selective iNOS inhibitorS-methylisothiourea abolished the protective effect of anisomycin. Furthermore, postischemic cardioprotective effect of anisomycin was absent in mice with targeted ablation of iNOS gene but not in the wild-type B6.129 mice. For the first time, these results suggest that direct pharmacological activation of p38 triggers delayed preconditioning by signaling mechanism involving NF-&kgr;B activation and synthesis of NO from iNOS.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Cation channels activated by Ca2+store depletion have been proposed to mediate Ca2+influx in vascular smooth muscle cells. The aim of this study was to determine if store-operated channels have a functional role in pulmonary artery smooth muscle cells (PASMCs). In intact rat pulmonary artery rings, cyclopiazonic acid (CPA) produced a sustained contraction that was resistant to inhibition by nifedipine, but abolished in Ca2+-free solution and 50% blocked in the presence of 6 &mgr;mol/L Cd2+, 10 &mgr;mol/L Ni2+, 600 &mgr;mol/L La3+, and 7 &mgr;mol/L SKF96365. In freshly isolated PASMCs loaded with fura-2, CPA increased the intracellular Ca2+concentration by stimulating dihydropyridine-resistant Ca2+influx, which was ≈50% blocked by 10 &mgr;mol/L Ni2+and 7 &mgr;mol/L SKF96365. In perforated-patch recordings, CPA activated a sustained inward current at negative membrane potentials, which persisted in cells dialyzed with BAPTA, showed a near linear dependence on membrane potential when Cs+was the main intracellular cation, and was blocked by Ni2+, Cd2+, and SKF96365 at concentrations preventing contraction. The current showed a bimodal dependence on extracellular Ca2+, being enhanced 2-fold in the absence of Ca2+and around 10-fold on reducing Ca from 1.8 to 0.2 mmol/L. RT-PCR revealed the expression of Trp1, Trp3, Trp4, Trp5, and Trp6 mRNA, whereas immunostaining identified Trp1, Trp3, Trp4, and Trp6 channel proteins in isolated PASMCs. At least one of these subunits may contribute to cation channels in PASMCs, which are activated by store depletion to bring about Ca2+influx and contraction.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Atherosclerosis is a disease of the arterial wall that seems to be tightly modulated by the local inflammatory balance. Whereas a large body of evidence supports a role for proinflammatory mediators in disease progression, the understanding of the role of the antiinflammatory component in the modulation of plaque progression is only at its beginning. TGF-&bgr;1, -&bgr;2, and -&bgr;3 are cytokines/growth factors with broad activities on cells and tissues in the cardiovascular system and have been proposed to play a role in the pathogenesis of atherosclerosis. However, no study has examined the direct role of TGF-&bgr; in the development and composition of advanced atherosclerotic lesions. In the present study, we show that inhibition of TGF-&bgr; signaling using a neutralizing anti–TGF-&bgr;1, -&bgr;2, and -&bgr;3 antibody accelerates the development of atherosclerotic lesions in apoE-deficient mice. Moreover, inhibition of TGF-&bgr; signaling favors the development of lesions with increased inflammatory component and decreased collagen content. These results identify a major protective role for TGF-&bgr; in atherosclerosis.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID