V patogenezi nefropatie krys způsobené aminonukleosidem puromycinu (PAN) se významná role připisuje zvýšené tvorbě reaktivních metabolitů kyslíku (RMK) v glomerulu. Doklady pro tuto hypotézu jsou založeny na poznatku, že látky, které tlumí tvorbu nebo odstraňují RMK, zmírňují proteinurii při PAN. Přímé měření tvorby RMK v izolovaných glomerulech by mohlo tuto hypotézu potvrdit. Inhibitor fosfodiesterázy IV - rolipram - tlumí tvorbu RMK v izolovaných glomerulech. Lze soudit, že by mohl zmírnit klinické projevy PAN. Chemiluminiscenční metodou jsme měřili tvorbu RMK na vrcholu proteinurie v suspenzi izolovaných glomerulů. V jiném pokusu jsme krysám 1 hodinu před a 1 hodinu po podání aminonukleosidu puromycinu aplikovali 25 mg/100 g tělesné váhy rolipramu. Kontrolním krysám byl aplikován pouze aminonukleosid puromycinu. Tvorba RMK izolovanými glomeruly krys s PAN byla statisticky významně nižší (p<0,01) než u kontrol. Inhibitor fosfodieterázy IV - rolipram neměl vliv na výši proteinurie krys s PAN. Závěry: Studie nepotvrdila domněnku o zvýšené tvorbě RMK v glomerulech krys s PAN. Nález jejich snížené tvorby na vrcholu proteinurie však nevylučuje jejich zvýšenou tvorbu v časově omezeném období PAN. Inhibitorem fosfodiesterázy IV, rolipramem, aplikovaným v časném období, se nepodařilo zmírnit klinické projevy PAN, ačkoliv lze soudit, že potlačil tvorbu.

A major role in attributed, in the pathogenesis of puromycin aminonucleoside nephropathy (PAN), to increased rates of production of reactives oxygen metabolites (ROM) in the glomerulus. Evidence for this hypothesis is based on the finding that substances either inhibiting ROM formation or ROM seavengers decrease proteinuria in PAN. Direct measurement of the rate of ROM production in isolated glomeruli could confirm this hypothesis. Rolipram, a phosphodiesterase IV inhibitor, inhibits ROM formation in isolated glomeruli. The implication is it could attenuate the clinical manifestations of PAN. Using chemiluminiscence, we measured ROM formation at peak proteinuria in a suspension of isolated glomeruli. In another experiment, rats were administered rolipram at a dose of 25 mg/100 g b.w. 1 hour before and 1 hour after the administration of puromycin aminonucleoside. Control rats were administered puromycin aminonucleoside only. The rate of ROM formation by isolated glomeruli of rats with PAN was significantly lower (P<0.01) compared with the controls. The phosphodiesterase inhibitor rolipram had no effect on the magnitude of proteinuria in rats with PAN. Conclusions: The study did not confirm the hypothesis of an increased rate of ROM formation in the glomeruli of rats with PAN. However, the finding of their reduced rate of formation at peak proteinuria does not rule out an increased rate of production within the limited period of PAN. The phosphodiesterase inhibitor rolipram administered at an early period, was unable to attenuate the clinical manifestations of PAN while presumably inhibiting ROM formation.

• MeSH
• glomerulus patologie   sekrece   účinky léků   MeSH
• inhibitory fosfodiesteras MeSH
• krysa rodu rattus MeSH
• luminiscence MeSH
• modely nemocí na zvířatech MeSH
• puromycin aminonukleosid škodlivé účinky   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• rolipram farmakologie   terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• přehledy MeSH
• srovnávací studie MeSH

In previous studies we observed that inhibition of cyclic 3',5'-nucleotide phosphodiesterase (PDE) isozymes, namely isozyme PDE3, suppresses proliferation of rat renal glomerular mesangial cells in vitro and in vivo. To determine whether activation of the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling pathway coupled to specific PDE isozymes modulates accelerated proliferation of renal epithelial cells, we investigated the effect of selective PDE isozyme inhibition on renal epithelial cell proliferation induced in rats by injection of folic acid (FA). In extracts from suspensions of renal cortical tubules, cAMP was metabolized predominantly by isozyme PDE4; activity of PDE3 was about three times lower. The increase in proliferative activity of renal cortical tissue from FA-injected rats, evaluated by immunostaining with Mib-1 antibody, was limited to tubular epithelial cells. Administration of the PDE3 inhibitors cilostazol or cilostamide together with the PDE4 inhibitor rolipram blocked mitogenic synthesis of DNA, as determined by (3H)-thymidine incorporation into renal cortical DNA, in FA-treated rats. FA injection caused an increase of more than 10-fold in proliferating cell nuclear antigen (PCNA) in renal cortical tissue; administration of the potent PDE3 inhibitor lixazinone or, to a lesser degree, cilostazol suppressed these high PCNA levels, whereas rolipram alone had no effect. The results indicate that FA-stimulated in vivo proliferation of renal tubular epithelial cells is down-regulated by activation of a cAMP-PKA signaling pathway linked to PDE3 isozymes. These observations are consistent with the notion that negative crosstalk between cAMP signaling and mitogen-stimulated signaling pathways regulates mitogenesis of renal cells of different terminal differentiation, including tubular epithelial cells.

• MeSH
• AMP cyklický * metabolismus   MeSH
• buněčné dělení účinky léků   MeSH
• cAMP-fosfodiesterasy * antagonisté a inhibitory   metabolismus   MeSH
• chinazoliny farmakologie   MeSH
• chinolony farmakologie   MeSH
• cyklické nukleotidfosfodiesterasy, typ 3 MeSH
• down regulace fyziologie   MeSH
• inhibitory fosfodiesteras * farmakologie   MeSH
• izoenzymy antagonisté a inhibitory   metabolismus   MeSH
• krysa rodu rattus MeSH
• kyselina listová farmakologie   MeSH
• ledvinové kanálky * cytologie   metabolismus   účinky léků   MeSH
• potkani Sprague-Dawley MeSH
• proliferační antigen buněčného jádra analýza   MeSH
• proteinkinasy závislé na cyklickém AMP metabolismus   MeSH
• pyrrolidinony farmakologie   MeSH
• rolipram MeSH
• signální transdukce účinky léků   MeSH
• tetrazoly farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH

We studied interactions between the mitogen-activated protein kinase (MAPK) signalling pathway and cAMP-protein kinase (PKA) signaling pathway in regulation of mitogenesis of mesangial cells (MC) determined by [3H]thymidine incorporation, with or without added EGF. Forskolin or dibutyryl cAMP strongly (by 60-70%) inhibited [3H]thymidine incorporation into MC. Cilostamide, lixazinone or cilostazol selective inhibitors of cAMP-phosphodiesterase (PDE) isozyme PDE-III, inhibited mitogenesis to similar extent as forskolin and DBcAMP and activated in situ PKA, but without detectable increase in cAMP levels. Cilostamide and cilostazol were more than three times more effective at inhibiting mesangial mitogenesis than rolipram and denbufylline, inhibitors of isozyme PDE-IV, even though PDE-IV was two times more abundant in MC than was PDE-III. On the other hand, when incubated with forskolin, rolipram-enhanced cAMP accumulation was far greater (10-100x) than with cilostamide. EGF increased MAPK activity (+300%); PDE isozyme inhibitors which suppressed mitogenesis also inhibited MAPK. PDE isozyme inhibitors also suppressed PDGF-stimulated MC proliferation. We conclude that cAMP inhibits the mitogen-dependent MAPK-signaling pathway probably by decreasing the activity of Raf-1 due to PKA-catalyzed phosphorylation. Further, we surmise that minor increase in the cAMP pool metabolized by PDE-III is intimately related to regulation of mesangial proliferation. Thus, PDE isozyme inhibitors have the potential to suppress MC proliferation by a focused effect upon signaling pathways.

• MeSH
• cAMP-fosfodiesterasy * antagonisté a inhibitory   MeSH
• chinolony farmakologie   MeSH
• destičkový růstový faktor farmakologie   MeSH
• epidermální růstový faktor farmakologie   MeSH
• glomerulární mesangium cytologie   enzymologie   účinky léků   MeSH
• izoenzymy * antagonisté a inhibitory   MeSH
• krysa rodu rattus MeSH
• kultivované buňky MeSH
• potkani Sprague-Dawley MeSH
• proteinkinasy závislé na cyklickém AMP * fyziologie   MeSH
• proteinkinasy závislé na vápníku a kalmodulinu metabolismus   MeSH
• pyrrolidinony farmakologie   MeSH
• rolipram MeSH
• thymidin metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH