RESUMO
beta-Adrenergic agonists induce muscle hypertrophy in mammalian species and alter the extractable activity of calpain proteinase and its specific endogenous inhibitor calpastatin. The effects on skeletal and cardiac muscle calpastatin of continuously infusing a group of pigs for 7 days with the physiological agonist epinephrine (0.15 microg/kg/min) were examined and compared with a placebo group. Basal levels of extractable calpastatin activity were higher in cardiac than skeletal muscle and epinephrine infusion increased the extractable activity in both muscle types (P < 0.05). An anti-recombinant porcine calpastatin antiserum detected a 135-kDa band and a 145/135-kDa doublet on Western blots of skeletal and cardiac extracts, respectively. Epinephrine infusion increased the 135-kDa band in skeletal muscle (P < 0.05), while the ratio of 145/135 kDa in cardiac muscle was decreased (P < 0.05). From Northern blots, the patterns of calpastatin mRNA species were similar in the two muscle types, two major transcripts at 5.8 and 3. 2 kb in cardiac muscle, with equivalent bands in skeletal muscle of 5.4 and 2.8 kb. A faint 7.9-kb band was also detected in skeletal muscle. Epinephrine infusion had no effect on skeletal calpastatin mRNA but tended to increase the 5.8-kb mRNA in cardiac muscle (P = 0. 053). These data indicate a differential response of the two muscle types to mildly elevated plasma epinephrine concentration and the response to elevated epinephrine may be at the translational or posttranslational level. Therefore, this type of stimulus appears to be less effective at perturbing calpastatin gene transcription than certain orally administered synthetic beta-adrenergic agonists.
Assuntos
Proteínas de Ligação ao Cálcio/genética , Epinefrina/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Músculo Esquelético/metabolismo , Miocárdio/metabolismo , Animais , Northern Blotting , Western Blotting , Proteínas de Ligação ao Cálcio/análise , Proteínas de Ligação ao Cálcio/isolamento & purificação , Epinefrina/administração & dosagem , Epinefrina/sangue , Feminino , Infusões Intravenosas , Peso Molecular , RNA Mensageiro/genética , Suínos , Transcrição Gênica/efeitos dos fármacosAssuntos
Proteínas de Ligação ao Cálcio/metabolismo , Calpaína/antagonistas & inibidores , Músculo Esquelético/metabolismo , Miocárdio/metabolismo , Processamento Alternativo , Animais , Proteínas de Ligação ao Cálcio/química , Proteínas de Ligação ao Cálcio/genética , Expressão Gênica , Técnicas In Vitro , Especificidade de Órgãos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , SuínosRESUMO
A novel bisegmented double-stranded RNA virus has been isolated from water processed from Thirlmere reservoir. The virus is icosahedral, 58 nm in diam., has a buoyant density of 1.32 g/ml in CsCl, has an S value of 400 and a RNA/protein ratio of 0.087. The two linear segments of RNA have approx. mol. wt. of 2.26 X 10(6) and 2.09 X 10(6). The virus contains six polypeptides. The virus was isolated in Drosophila melanogaster cells and fails to replicate in other insect, amphibian, avian, piscine, mammalian and plant cells tested. The virus is biochemically different from infectious pancreatic necrosis virus (IPNV) and Drosophila X virus (DXV). The virus is also serologically unrelated to IPNV (strain Sp) and another invertebrate pathogenic virus, Tellina virus 1. The virus shares common antigens with DXV but is not completely identical.
