Citric acid is recognized and utilized as a dietary supplement for its ability to eliminate fatigue. However, the molecular and cellular mechanism underlying this effect has not been elucidated. This study investigate...Citric acid is recognized and utilized as a dietary supplement for its ability to eliminate fatigue. However, the molecular and cellular mechanism underlying this effect has not been elucidated. This study investigated the effect of intragastric citric acid administration on the energy metabolism and gene expression in the skeletal muscles of mice that had been fasted without exercise, using biochemical analyses of metabolic indicators and DNA microarrays. Expression of the genes involved in the glycolysis, tricarboxylic acid cycle and β-oxidation of fatty acids were not affected by citric acid administration. However, citric acid increased the level of blood glucose and expression of the phosphoenolpyruvate carboxykinase gene. These results indicate that citric acid ingestion may eliminate fatigue by promoting gluconeogenesis.展开更多
To evaluate the effect of proteolytic enzymes on the absorption of insulin in the buccal mucosa, the trichloroacetic acid (TCA) method was used to estimate the degradation of insulin under different conditions in the ...To evaluate the effect of proteolytic enzymes on the absorption of insulin in the buccal mucosa, the trichloroacetic acid (TCA) method was used to estimate the degradation of insulin under different conditions in the buccal mucosal homogenates. In vivo experiments estimating the enhancement of hypoglycaemic effect by enzyme inhibitors were also conducted. The results showed that proteolytic enzymes in the buccal mucosa were less active than in the intestine. Bacitracin, aprotinin and sodium deoxycholate could inhibit the degradation of insulin in the buccal mucosal homogenates. The degradation of insulin in buccal mucosal homogenates of normal hamsters was smaller than that of diabetic hamsters. In vivo experiments of hypoglycaemia supported the in vitro results. When given buccally, bacitracin, aprotinin and sodium deoxycholate could increase the relative pharmacological bioavailability of insulin. When co-administered with aprotinin(0.1%), bacitracin(0.5%) and sodium deoxycholate(5%), the relative pharmacological bioavailabilities of insulin were 4.84%, 6.60% and 14.95% respectively. The in vitro and in vivo results suggest that proteolytic enzymes are present in the buccal mucosa, which limit absorption of insulin. Co-administration with some enzyme inhibitors can improve the bioavailability of insulin via buccal delivery and sodium deoxycholte is more efficient than some enzyme inhibitors used for improving buccal absorption.展开更多
文摘Citric acid is recognized and utilized as a dietary supplement for its ability to eliminate fatigue. However, the molecular and cellular mechanism underlying this effect has not been elucidated. This study investigated the effect of intragastric citric acid administration on the energy metabolism and gene expression in the skeletal muscles of mice that had been fasted without exercise, using biochemical analyses of metabolic indicators and DNA microarrays. Expression of the genes involved in the glycolysis, tricarboxylic acid cycle and β-oxidation of fatty acids were not affected by citric acid administration. However, citric acid increased the level of blood glucose and expression of the phosphoenolpyruvate carboxykinase gene. These results indicate that citric acid ingestion may eliminate fatigue by promoting gluconeogenesis.
文摘To evaluate the effect of proteolytic enzymes on the absorption of insulin in the buccal mucosa, the trichloroacetic acid (TCA) method was used to estimate the degradation of insulin under different conditions in the buccal mucosal homogenates. In vivo experiments estimating the enhancement of hypoglycaemic effect by enzyme inhibitors were also conducted. The results showed that proteolytic enzymes in the buccal mucosa were less active than in the intestine. Bacitracin, aprotinin and sodium deoxycholate could inhibit the degradation of insulin in the buccal mucosal homogenates. The degradation of insulin in buccal mucosal homogenates of normal hamsters was smaller than that of diabetic hamsters. In vivo experiments of hypoglycaemia supported the in vitro results. When given buccally, bacitracin, aprotinin and sodium deoxycholate could increase the relative pharmacological bioavailability of insulin. When co-administered with aprotinin(0.1%), bacitracin(0.5%) and sodium deoxycholate(5%), the relative pharmacological bioavailabilities of insulin were 4.84%, 6.60% and 14.95% respectively. The in vitro and in vivo results suggest that proteolytic enzymes are present in the buccal mucosa, which limit absorption of insulin. Co-administration with some enzyme inhibitors can improve the bioavailability of insulin via buccal delivery and sodium deoxycholte is more efficient than some enzyme inhibitors used for improving buccal absorption.
