【摘要】 边缘性缺乏抗坏血酸之豚鼠,于三周内其肝脏及小肠粘膜3-羟-3-甲基戊二酰辅酶A还原酶(HMGR)活力均下降到原有水平的50％,但肝脏胆固醇7α-羟化酶活力尚无显著性改变。坏血病豚鼠(三周内)上述几种酶活力都下降至原有水平的50％左右。豚鼠摄取抗坏血酸不足,其血清总胆固醇浓度显著增加,而血清高密度脂蛋自胆固醇浓度显著减少,其改变程度与抗坏血酸缺乏状况一致。更多还原

【Abstract】 The effect of nutritional status of ascorbic acid on the activity of hepatic 3-hydroxy-3-methyl glutaryl coenzyme A reductase (HMGR), cbolesterol 7α-hydroxylase, small intestine mucosal HMGR and serum cholesterol was investigated. Groups of female guinea pig were fed scorbutogenic diet (scorbutic group) and with scorbutogenic diet supplemented with 0.8 mg ascorbic acid/animal/day (marginal deficiency group) respectively for three weeks. In comparison the normai with marginal deficiency group, the later exhibited lowered hepatic aud small intestine mucosal HMGR activity and reduced high density lipoprotein cholesterol (HDL-ch) content. The changes in activity of hepatic cholesterol 7α-hydroxylase and serum total cholesterol were of no signifi-cance. The scorbutic group exhibited lowered activity of hepatic and small intestine mucosal HMGR, hepatic cholesterol 7α-hydroxylase, lowered content of HDL-ch and increased content of serum total cholesterol. Our data clearly demonstrated that the increase of serum total cholesterol content is result of decreased capacity to synthesize HDL-ch and bile acid in ascorbic acid deficiency animals. The main lesion of ascorbic acid dcficiency animal is the marked inhibition of hepatic and small intestine mucosal HMGR and hepatic cholesterol 7α-hydroxylase and decreased sythesizing of HDL-ch. Ginters had suggested that the elevated half life of serum cholesterol and lowered turnover rate of ascorbic acid deficienty guinea pigs were due to the decreased conrersion of cholesterol to bile acid. Our result suggested that besides the decrease in conversion of cholesterol to bile acid, the lowered activity of hepatic and small intestine mucosal HMGR is probably is also the cause for elevated half life of serum cholesterol and lowered turnover rate of cholesterol of guinea pigs suffering ascorbic acd deficiency.更多还原