RESUMO
OBJECTIVE: To observe effects of restraint position on the changes of diaphragmatic mechanical characteristic in rats, and try to explore the role of nitric oxide (NO). METHODS: Rat model of restraint position was established. Rats were divided into control group, restraint position 12h and 24h groups. The markers of respiratory functions in vivo and the biomechanical markers of diaphragmatic characteristic ex vivo were evaluated. Serum NO levels were measured with spectrophotometry. The expressions of nNOS and iNOS mRNA in diaphragm were detected using RT-PCR. RESULTS: Compared with control group, respiratory rate, tidal volume and minute ventilation were significantly decreased in the restraint position 12h and 24h groups. Pt of diaphragm significantly decreased and force-generating capacity reduced at low frequency stimulation in 12h group. Force-generating capacity over the full range reduced at low and high frequency stimulation in 24h group. Pt of diaphragm in control and restraint position groups increased after L-NNA pre-incubation. Force-frequency relationship after L-NNA pre-incubation reduced in 24h group. NO level in serum increased significantly in the restraint position groups. Diaphragmatic nNOS mRNA expression was upregulated significantly in the restraint position groups. CONCLUSION: Restraint position induces the decreasement of diaphragmatic contractility and the decreasement is mediated by NO from diaphragm or circulation blood.
Assuntos
Diafragma/fisiopatologia , Contração Muscular/fisiologia , Óxido Nítrico/sangue , Postura , Restrição Física , Animais , Fenômenos Biomecânicos , Diafragma/metabolismo , Diafragma/fisiologia , Masculino , Tono Muscular/fisiologia , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Transtornos Respiratórios/etiologia , Transtornos Respiratórios/fisiopatologia , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
OBJECTIVE: The present study aimed to estimate the association between susceptibility to migraine and the 12-nucleotide insertion/deletion (indel) polymorphism in promoter region of alpha(2B)-adrenergic receptor gene (ADRA2B). METHODS: A case-control study was carried out in Chinese Han population, including 368 cases of migraine and 517 controls. Genomic DNA was extracted from blood samples, and DNA fragments containing the site of polymorphism were amplified by PCR. Data were adjusted for sex, age, migraine history and family history, and analyzed using a logistic regression model. RESULTS: There was no association between indel polymorphism and migraine, at either the allele or the genotype level. CONCLUSION: These findings do not support a functional significance of ADRA2B indel polymorphism at position -4825 relative to the start codon in the far upstream region of the promoter in the present migraine subjects.
