Inhibition ofin-vitro amino acid incorporation by the carcinogen N-methyl N’-nitro N-nitrosoguanidine

Bagewadikar, R. S.; Bhattacharya, R.K.

doi:10.1007/bf02702728

Cited by 2 publications

(3 citation statements)

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“…It was also observed that MNNG caused a direct inactivation of the biologic activity of mucosal polyribosome. These effects are very similar to those found in liver systems (13)(14)(15). Since a similar inhibition is evident in stomach mucosa when MNNG is fed orally, it is reasonable to assume that MNNG inhibits protein synthesis by a similar mechanism in stomach, its target organ, as it does in liver.…”

Section: Discussionsupporting

confidence: 75%

“…Incorporation of [14C]leucine and other labeled amino acids in postmitochondrial supernatant of mucosa was measured according to the procedure described earlier (13). The method of [14C]leucine incorporation into polyribosomal protein was similar to the one described previously (14) except that 1 A, , unit polyribosome and 0.5 mg enzyme protein (pH 5) were used for each 100 p1 reaction mixture. Each in vitro assay was conducted in duplicate and each experiment was repeated with the same or other preparations of mucosal fractions.…”

Section: In Vitro Incorporation Studiesmentioning

confidence: 99%

“…Among the biochemical effects of MNNG in model systems, protein synthesis has been investigated most thoroughly. Using cell-free systems from rat liver we have demonstrated that MNNG inhibits protein synthesis (13)(14)(15) through alteration of activities of tRNA (14-16) and ribosome (14,15) involving methylation and nitroguanidination, respectively. It is important to ascertain if MNNG has such a role in the stomach mucosa, probably the first site of exposure, in a susceptible species.…”

Section: Introductionmentioning

confidence: 99%

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Effect of N‐methyl‐N′‐Nitro‐N‐nitrosoguanidine on amino acid incorporation into mucosal protein of rat stomach

Bagewadikar

Bhattacharya

1992

J. Biochem. Toxicol.

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Administration of the carcinogenic N-nitroso compound, N-methyl-N'-nitro-N-nitrosoguanidine in drinking water (0.5 mg/mL) to male Wistar rats for 1 week caused impairment of in vivo and in vitro incorporation of [14C]leucine into stomach mucosal protein. This impairment gradually returned to normal after 4 weeks. Uptake of [14C]leucine into mucosal protein was significantly inhibited after in vitro treatment of stomach mucosa with the carcinogen. Addition of the N-nitroso compound in a cell-free system using postmitochondrial supernatant prepared from stomach mucosa also showed inhibition of amino acid incorporation. Using a more defined system consisting of purified polyribosome from stomach mucosa and pH 5 enzyme fraction derived from liver it was further demonstrated that the carcinogen purturbed protein synthesizing ability of polyribosome, under both in vivo and in vitro treatment conditions. In these respects this carcinogen has similar action on the target tissue of stomach as in the liver, although the in vivo effect may be related more to toxicity than carcinogenicity.

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Section: Discussionsupporting

confidence: 75%

Section: In Vitro Incorporation Studiesmentioning

confidence: 99%