Impact of copper on the oxidative metabolism of the fry of common carp, Cyprinus carpio (Linn.) at different pH.

In order to evaluate the impact of copper on the energetics of a fish, the levels of glucose, glycogen, pyruvate and lactate, the rate of tissue oxygen consumption and the activities of glycogen phosphorylase, isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) were estimated in the whole body of the fry of Cyprinus carpio immediately after 1, 7, 15 and 30 days on exposure to a sublethal concentration of copper 0.08 mgl(-1) at pH 7.5 (normal), 6.0 (weak acidic) and 9.0 (weak alkaline). Aprogressive increase in glucose level and glycogen phosphorylase activity with the corresponding decrease in glycogen level over the time of exposure at pH 7.5 indicated glycogenolysis. Increase in the rate of oxygen consumption, pyruvate level and ICDH and SDH activities at days 1 and 7 (day 1 > 7) followed by their decrease at days 15 and 30 (day 15 < 30) at pH 7.5 indicated an initial elevation in the energetics of the fish fry with a gradual suppression of it on prolonged exposure. During this period the animal might have relied more on energetically less efficient glycolysis as evident by the progressive increase in the level of lactate and LDH activity. The degree of glycogenolysis was relatively more at pH 6.5 than at pH 7.5. At that pH, a progressive decrease in glucose level with an increase in the pyruvate and lactate levels and in LDH activity and a decrease in the rate of oxygen consumption and ICDH and SDH activities revealed greater reliance of the fish on anaerobic glycolysis than on oxidative metabolism. At pH 9.0 also the fish fry initially exhibited glycogenolysis, but gradually it came to normal on day 30 (day 1 > 7 > 15 > 30). Decrease in the glucose level, increase in pyruvate level, rate of oxygen consumption, and ICDH and SDH activities at all the days of exposure suggested an elevation in oxidative metabolism, but it also came to normal on prolonged exposure. Even the lactate level and LDH activity initially increased but gradually reached to normal on day 30. These results indicated that copper suppresses the energetics of the fish fry at pH 6.0, elevates at pH 9.0 relative to the changes at pH 7.5 suggesting that the toxicity of copper is dependent on pH of the water.

Role of pectin from cucumber (Cucumis sativus) in modulation of protein kinase C activity and regulation of glycogen metabolism in rats.

The regulatory role of protein kinase C (PKC) in glycogen metabolism in pectin fed rats was investigated. Administration of pectin (5 g/kg body wt/day) from cucumber (Cucumis sativius L.) led to inhibitory effects on PKC activity in the liver of rats. In the brain and pancreas, PKC activity was significantly higher in pectin-treated rats as compared to the control group. Level of blood glucose was significantly lowered and the level of glycogen in the liver was significantly increased in pectin-administered rats. Glycogen synthase activity was enhanced, while glycogen phosphorylase enzyme showed inhibition in pectin-treated rats. Results indicated that pectin administration might have caused an increase in the secretion of the insulin, which, in turn, had a stimulatory effect on the PKC activity in the pancreas. The decreased PKC activity in the liver and increased PKC activity in the brain and pancreas on pectin administration indicated enhanced glycogenesis and reduced glycogenolysis.

Glicogênio-fosforilase: marcador promissor de infarto do miocárdio? / Glycogen phosphorylase: promising marker of acute myocardial infarction?

A glicogênio-fosforilase (GP) é uma enzima que participa do processo de glicogenólise, fundamental em casos de isquemia e hipoxia tissular. Possui três isoenzimas, sendo que a GPBB tem despertado muito interesse dos pesquisadores por estar presente de forma representativa no miocárdio, podendo tornar-se um futuro marcador de infarto. Seus níveis séricos elevam-se nas primeiras horas do início dos sintomas e retornam aos valores normais em 24 a 48 horas, demonstrando-se muito sensível. A especificidade da GPBB só não é confiável quando o paciente apresenta danos cerebrais concomitantes, isso porque a predominância da GPBB no organismo humano é no cérebro. Vários autores têm realizado extensa revisão do tema, abordando os principais aspectos desse possível novo marcador.