Expression and specific activities of carbamoyl phosphate synthetase 1 in chronic hypoxic rats

Background: Urea biosynthesis is a very important process in the liver which needs ATP, CO2 and functional mitochondria or aerobic condition. Liver can adapt to hypoxic condition, generally and locally. This study aimed to analyze the effect of chronic hypoxia on liver urea biosynthesis as indicated by the level and specific activity of mRNA of carbamoyl phosphate synthetase 1 (CPS1), a key enzyme in urea biosynthesis in hypoxic rats.Methods: 20 male Sprague-Dawley rats were placed in hypoxic chamber supplied by a mixture of 10% O2 and 90% N2. Five rats were sacrificed at 1, 3, 5, and 7 days after exposure. Liver homogenates were analyzed for HIF-1 (hypoxia inducible factor-1) by ELISA, CPS1 mRNA by real time RT-PCR and CPS1 enzymatic specific activities by Pierson method. Data were analyzed by ANOVA test and Pearson correlation.Results: The HIF-1 in liver increased significantly, as well as CPS1 mRNA and CPS1 enzymatic activities (p<0.05). There was a strong correlation (r=0.618; p<0.01) between the level of CPS1 mRNA and CPS1 enzymatic activities, moderate correlation between HIF-1 and CPS1 mRNA (r=0.419; p<0.05) but no correlation between HIF-1 and CPS1 enzymatic activities. The study indicated that urea biosynthesis in liver was affected by hypoxia and partially under HIF-1 regulation. The study also found increase of urea and NH3 biosynthesis related to proteolysis as indicated by the decrease of total body weight and liver weight.Conclusion: There was an increase in the expression and specific activities of CPS1 in urea biosynthesis as a result of increasing proteolysis in chronic hypoxic condition.

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H,K-ATPase and carbonic anhydrase response to chronic systemic rat gastric hypoxia

Medical Journal of Indonesia ◽

10.13181/mji.v24i3.1066 ◽

2015 ◽

Vol 24 (3) ◽

pp. 133-8

Author(s):

Ulfah Lutfiah ◽

Sri W.A. Jusman ◽

Mochammad Sadikin

Keyword(s):

Gastric Ulcer ◽

Carbonic Anhydrase ◽

Specific Activity ◽

Hypoxic Condition ◽

Control Group ◽

Sprague Dawley ◽

The Third ◽

Hcl Secretion ◽

Specific Activities

Background: Hypoxia may induce gastric ulcer associated with excessive hidrogen chloride (HCl) secretion. Synthesis of HCl involves 2 enzymes, H,K-ATPase and carbonic anhydrase (CA). This study aimed to clarify the underlying cause of gastric ulcer in chronic hypoxic condition, by investigating the H,K-ATPase and CA9 response in rats.Methods: This study was an in vivo experiment, to know the relationship between hypoxia to expression of H,K-ATPase and CA9 mRNA, and H,K-ATPase and total CA specific activity of chronic systemic rat gastric hypoxia. The result was compared to control. Data was analyzed by SPSS. If the data distribution was normal and homogeneous, ANOVA and LSD post-hoc test were used. However, if the distribution was not normal and not homogeneous, and still as such after transformation, data was treated in non-parametric using Kruskal-Wallis and Mann Whitney test. Twenty five male Sprague-Dawley rats were divided into 5 groups: rats undergoing hypoxia for 1, 3, 5, and 7 days placed in hypoxia chamber (10% O2, 90% N2), and one control group. Following this treatment, stomach of the rats was extracted and homogenized. Expression of H,K-ATPase and CA9 mRNA was measured using real time RT-PCR. Specific activity of H,K-ATPase was measured using phosphate standard solution, and specific activity of total CA was measured using p-nitrophenol solution.Results: The expression of H,K-ATPase mRNA was higher in the first day (2.159), and drastically lowered from the third to seventh day (0.289; 0.108; 0.062). Specific activities of H,K-ATPase was slightly higher in the first day (0.765), then was lowered in the third (0.685) and fifth day (0.655), and was higher in the seventh day (0.884). The expression of CA9 mRNA was lowered progressively from the first to seventh day (0.84; 0.766; 0.736; 0.343). Specific activities of total CA was low in the first day (0.083), and was higher from the third to seventh day (0.111; 0.136; 0.144).Conclusion: In hypoxia condition, expression of H,K-ATPase and CA9 mRNA were decreased, but the specific activity of H,K-ATPase and total CA were increased.

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THE Ah PHENOTYPE. SURVEY OF FORTY-EIGHT RAT STRAINS AND TWENTY INBRED MOUSE STRAINS

Genetics ◽

10.1093/genetics/100.1.79 ◽

1982 ◽

Vol 100 (1) ◽

pp. 79-87

Author(s):

Daniel W Nebert ◽

Nancy M Jensen ◽

Hisashi Shinozuka ◽

Heinz W Kunz ◽

Thomas J Gill

Keyword(s):

Specific Activity ◽

Inbred Mouse ◽

Inbred Mouse Strain ◽

Mouse Strains ◽

Ah Receptor ◽

Inbred Mouse Strains ◽

Sprague Dawley ◽

Rat Strains ◽

Specific Activities ◽

Inbred Rat

ABSTRACT Forty-four inbred and four randombred rat strains and 20 inbred mouse strains were examined for their Ah phenotype by determining the induction of liver microsomal aryl hydrocarbon (benzo[a]pyrene) hydroxylase activity (EC 1.14.14.1) by intraperitoneal treatment with either β-naphthoflavone or 3-methylcholanthrene. All 48 rat strains were found to be Ah-responsive. The maximally induced hydroxylase specific activities of the ALB/Pit, MNR/Pit, MR/Pit, SHR/Pit, and Sprague-Dawley strains were of the same order of magnitude as the basal hydroxylase specific activities of the ACI/Pit, F344/Pit, OKA/Pit, and MNR/N strains. Six of the 20 mouse strains were Ah-nonresponsive (i.e. lacking the normal induction response and presumably lacking detectable amounts of the Ah receptor). The basal hydroxylase specific activities of the BDL/N, NFS/N, STAR/N, and ST/JN mouse strains were more than twice as high as the maximally induced hydroxylase specific activity of the CBA/HT strain.——To date, 24 Ah-nonresponsive mouse strains have been identified, out of a total of 68 known to have been characterized. The reasons for not finding a single Ah-nonresponsive inbred rat strain—as compared with about one Ah-nonresponsive inbred mouse strain found for every three examined—remain unknown.

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