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Effect of antidiuresis on renal creatine metabolism

100%

Garcia-Miranda P., Peral M. J., Ilundain A. A.

Journal of Physiology and Pharmacology

2010

tom 61

nr 1

83-88

The current work investigates whether creatine metabolism is involved in renal adaptation to dehydration. Wistar rats were either deprived of water or induced to drink water abundantly during 60 h. Cortical and medullar mRNA levels of Na+/Cl-/creatine transporter (CRT), l-arginine: glycine amidinotransferase (AGAT), guanidinoacetate methyltransferase (GAMT) and of the tonicity sensitive genes coding for aquaporin 2, Na+/Cl-/betaine transporter and glucocorticoid-inducible kinase were measured by real-time PCR assays. The activity of the CRT and that of Na+/-methyl-glucose transporter were evaluated in renal brush-border membrane vesicles. In water loaded animals, the mRNA levels of AGAT and CRT, and the activity of the CRT were greater in the cortex than in the medulla. GAMT mRNA levels were of similar magnitude and lower than those of AGAT mRNA. Dehydration decreased cortical and medullar AGAT and CRT mRNA levels and CRT activity and it did no affect GAMT mRNA abundance. These decreases were creatine specific because dehydration increased Na+/-methyl-glucose transporter activity and the mRNA abundance of aquaporin 2, Na+/Cl-/betaine transporter and glucocorticoid-inducible kinase. In conclusion, this is the first report showing that: i) the kidneys express significant amounts of GAMT mRNA, ii) dehydration down-regulates the expression of AGAT gene and iii) dehydration down-regulates CRT gene expression and activity.

Ontogeny regulates creatine metabolism in rat small and large intestine

84%

Garcia-Miranda P., Garcia-Delgado M., Peral M. J., Calonge M. L., Ilundain A. A.

Journal of Physiology and Pharmacology

2009

tom 60

nr 3

127-133

The ontogeny of intestinal CRT, AGAT and GAMT was investigated in foetuses, newborn, suckling, weaning and adult rats. In the colon, CRT mediates creatine transport because it was Na+- and Cl- dependent and inhibited by creatine and GPA. In addition, Northern assays showed two CRT transcripts (2.7-kb and 4.2-kb) and the in situ hybridisation revealed that CRT mRNA is restricted to the colon epithelial cells. The immunohistochemistry revealed that CRT protein was at the apical membrane of colon epithelia. Maturation decreased colonic CRT activity to undetectable levels and increased CRT mRNA abundance. Western assays revealed 57-, 65-, 80- and 116-kDa polypeptides at the intestinal apical membrane. The abundance of the 65-, 80- and 116-kDa polypeptides decreased with age, and that of 57-kDa was only observed in adult rats. The small and large intestine express AGAT and GAMT mRNAs. Maturation decreased AGAT mRNA abundance without affecting that of GAMT. For comparison, renal AGAT mRNA levels were measured and they were increased with age. The study reports for the first time that: i) the apical membrane of rat colon have an active CRT, ii) development down-regulates CRT activity via post-transcriptional mechanism(s), iii) the intestine might synthesize creatine and iv) intestinal and renal creatine synthesis is ontogenically regulated at the level of AGAT gene expression.

Ograniczanie wyników

2 Journal of Physiology and Pharmacology

2 Garcia-Miranda P.

2 Ilundain A. A.

2 Peral M. J.

1 Calonge M. L.

1 Garcia-Delgado M.

1 2010

1 2009

Wyniki wyszukiwania

Effect of antidiuresis on renal creatine metabolism

Ontogeny regulates creatine metabolism in rat small and large intestine