RESUMO
The etiology of anemia in cancer is not fully understood. A possible cause of the anemia of tumor-bearing animals could be a decreased activity in the enzymes of the heme-pathway. We report the enzyme activity of porphobilinogen-synthetase in the liver of Yoshida sarcoma-bearing rats. PBG-synthetase activity in the whole liver, is higher in tumor-bearing rats than in controls, although the enzyme activity by a gram of wet liver is decreased. Hence PBG-synthetase activity is not a limiting factor in the biosynthesis of heme in tumor-bearing animals.
Assuntos
Fígado/enzimologia , Sintase do Porfobilinogênio/metabolismo , Sarcoma de Yoshida/enzimologia , Animais , Masculino , Tamanho do Órgão , RatosRESUMO
Total content of cobalamins was estimated by an isotopic dilution technique in serum and liver of Yoshida sarcoma-bearing rats and in a group of control rats. Total levels of vitamin B12 were also measured in neoplastic tissue. Hydroxycobalamin, adenosylcobalamin, cyanocobalamin and methylcobalamin, were estimated by a chromato-bioautographic technique in the above mentioned tissues and animals. We found no significant difference between control and tumor-bearing rats with respect to the total content of vitamin B12 in the different tissues. This suggests that vitamin B12 requirements of neoplastic cells do not significantly deplete host cobalamin stores. We have also found no significant differences in the values of the different cobalamin coenzyme forms between the two groups of animals. This suggests that there is not preferential uptake of any host cobalamin fraction by the neoplastic cells. The four coenzyme-forms of cobalamin have been detected in Yoshida sarcoma. Adenosylcobalamin and cyanocobalamin are the major components of the pool of cobalamins of the tissue.
Assuntos
Fígado/metabolismo , Sarcoma de Yoshida/metabolismo , Vitamina B 12/metabolismo , Animais , Cobamidas/metabolismo , Hidroxocobalamina/metabolismo , Masculino , Ratos , Vitamina B 12/análogos & derivados , Vitamina B 12/sangueRESUMO
We have studied the effect of methylene blue on GSH and GSSG levels in rat blood, liver and kidney. Methylene blue treatment increases GSH levels and PBG-synthetase activity in erythrocytes while liver and kidney GSH and GSSG levels remain constant. These results indicate that methylene blue effect on PBG-synthetase activity in rat erythrocytes is mediated by an increase in blood GSH levels.
Assuntos
Glutationa/metabolismo , Azul de Metileno/farmacologia , Sintase do Porfobilinogênio/metabolismo , Animais , Eritrócitos/metabolismo , Glutationa/sangue , Rim/metabolismo , Fígado/metabolismo , Masculino , Oxirredução , Sintase do Porfobilinogênio/sangue , RatosRESUMO
Changes in blood glucose in response to glucagon and epinephrine administration, in rats bearing Yoshida solid sarcoma and Walker-256 carcinosarcoma have been studied, and in rats carrying Yoshida tumor which had received previously intraperitoneal glucose. The response to glucagon by tumor-bearing rats follows the control pattern but at a lower level of blood glucose. Rats which had received glucose before glucagon administration responded to this hormone as the control animals. These results indicate that glycogen metabolism in the host liver is not diturbed by the presence of the tumor.