Rhythmic daily changes in the Na,K-ATPase activity have been previously described for rat kidney cortex, showing two peaks: at 0900 h and 2100 h, and two valleys: at 1500 h and 0100 h - 0300 h. The oscillations in Na,K-ATPase activity are produced by an inhibitor, which binds the enzyme and is present in the rat blood plasma at valley times and absent or at very low concentrations at peak times. Since it has been demonstrated that active Na+ extrusion from the cells of several tissues depends not only on the Na,K-ATPase but also on the ouabaininsensitive Na-ATPase, we studied the activity of this latter enzyme of several rat tissues, i.e., kidney cortex, small intestine, liver, heart and red blood cells along the day. None of these tissues showed any variation of their Na-ATPase activity along the day. Preincubation of kidney cortex homogenates obtained at 0900 h, with blood plasma drawn at 0900 h and 1500 h, did not modify the Na-ATPase activity. Our results indicate that the Na- ATPase activity does not oscillate along the day. These results are in agreement with the idea that the Na-ATPase could partially compensate the Na+ transport affected by oscillations of the Na,K-ATPase activity.

• MeSH
• cirkadiánní rytmus MeSH
• erytrocyty enzymologie   MeSH
• játra enzymologie   MeSH
• krysa rodu rattus MeSH
• kůra ledviny enzymologie   MeSH
• ouabain MeSH
• potkani Sprague-Dawley metabolismus   MeSH
• sodíko-draslíková ATPasa metabolismus   MeSH
• srdeční komory enzymologie   MeSH
• tenké střevo enzymologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH

Akt kinase regulates numerous cell functions including glucose metabolism, cell growth, survival, protein synthesis, and control of local hemodynamics. mTOR is one of down-stream effectors of Akt involved in the initiation of protein translation. However, renal Akt signaling in Type 1 diabetes (DM) in vivo, in particular under the conditions reflecting differences in metabolic control, has received less attention. Renal cortical activity and expression of Akt and mTOR (kinase assay, western blotting) were determined in streptozotocin-diabetic rats (D) with different levels of glycemic control (blood glucose 22.0±1.0, 13.4±1.5, 8.1±0.4 mmol/l, p<0.05 between the groups), achieved by varying insulin treatment (0, 4 and 12 IU/day), and in control rats with (C4) or without (C) chronic insulin administration. Renal Akt activity was reduced in D rats without insulin treatment and severe hyperglycemia (D-0, -62 %, p<0.01 vs. C), partially restored in moderately hyperglycemic rats (D-4, -30 %, p<0.05 vs. C), and normalized in D rats with intensive insulin and tight metabolic control (D-12). Expression of active mTOR paralleled Akt activity in D-0 (-51 %, p<0.01 vs. C), but not in D-4 and D- 12 that demonstrated increases in active mTOR (+55 %, +80 % resp., p<0.05) as compared to C. Moreover, insulin activated renal Akt (+82 %, p<0.01), but not mTOR in C4. In conclusion, glycemic control and intensity of insulin treatment are important modulators of renal Akt and mTOR activity in diabetes. While Akt activity is reversible by tight metabolic control, combination of hyperglycemia and insulin treatment resulted in enhancement of mTOR activity. In addition to Akt, other signaling pathways likely contribute to regulation of renal mTOR activity in diabetes.

• Klíčová slova
• Akt kinase, Diabetic nephropathy, Insulin, Mammalian targetof rapmycin, mTOR,
• MeSH
• diabetes mellitus 1. typu enzymologie   farmakoterapie   komplikace   MeSH
• diabetické nefropatie enzymologie   etiologie   farmakoterapie   MeSH
• experimentální diabetes mellitus enzymologie   farmakoterapie   komplikace   MeSH
• financování organizované MeSH
• fosforylace MeSH
• hypoglykemika terapeutické užití   MeSH
• inzulin krev   terapeutické užití   MeSH
• kinasa 3 glykogensynthasy metabolismus   MeSH
• krevní glukóza metabolismus   MeSH
• krysa rodu rattus MeSH
• kůra ledviny enzymologie   účinky léků   MeSH
• proteinkinasy metabolismus   MeSH
• protoonkogenní proteiny c-akt metabolismus   MeSH
• signální transdukce MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH

• MeSH
• aktivace enzymů genetika   MeSH
• cvičení fyziologie   MeSH
• dospělí MeSH
• fyziologický stres enzymologie   MeSH
• krysa rodu rattus MeSH
• kůra ledviny enzymologie   MeSH
• lidé MeSH
• prekurzory enzymů krev   metabolismus   MeSH
• renin krev   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH

• MeSH
• karcinom enzymologie   MeSH
• kůra ledviny analýza   enzymologie   MeSH
• lidé MeSH
• nádory ledvin enzymologie   MeSH
• porfyrinogeny analýza   MeSH
• porfyriny analýza   MeSH
• Check Tag
• lidé MeSH

• MeSH
• alanintransaminasa analýza   MeSH
• experimenty na zvířatech MeSH
• kůra ledviny enzymologie   MeSH
• prasata MeSH

• MeSH
• dřeň ledvin enzymologie   fyziologie   MeSH
• fyziologický stres MeSH
• katecholaminy fyziologie   MeSH
• krysa rodu rattus MeSH
• kůra ledviny enzymologie   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH

• MeSH
• biotransformace MeSH
• enzymová indukce účinky léků   MeSH
• játra enzymologie   MeSH
• králíci MeSH
• kůra ledviny enzymologie   MeSH
• methyltransferasy biosyntéza   metabolismus   MeSH
• nemoci jater enzymologie   MeSH
• nemoci ledvin enzymologie   chemicky indukované   MeSH
• organortuťnaté sloučeniny MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• mužské pohlaví MeSH
• zvířata MeSH