Davis F B, Davis P J, Nat G, Blas S D, MacGillivray M, Gutman S, Feldman M J
Diabetes. 1985 Jul;34(7):639-46. doi: 10.2337/diab.34.7.639.
To characterize endogenous control mechanisms for human erythrocyte membrane Ca2+-ATPase ("calcium pump") activity, we studied the effect of changes in blood glucose concentration in vivo within the physiologic range on Ca2+-ATPase activity in red cells. Red cells obtained in the course of induced hyperglycemia were also studied to determine susceptibility of membrane Ca2+-ATPase to stimulation in vitro by thyroid hormone and calmodulin, both of which have been shown previously to enhance Ca2+-ATPase activity. Oral glucose administration (75 g) to eight healthy, adult subjects induced predictable increases in concentrations of blood glucose and immunoreactive insulin. Basal levels of activity of Ca2+-ATPase in red cells obtained after glucose ingestion fell 55% (P less than 0.025) by 30 min after glucose with recovery of enzyme activity to levels not significantly different from basal by 60 min. Activity of red cell Ca2+-ATPase at time zero was significantly stimulated in vitro by thyroxine (T4, 10(-10) M), triiodo-L-thyronine (T3, 10(-10) M), and calmodulin (100 ng/mg membrane protein). In vivo glucose administration led to depression of red cell enzyme responsiveness in vitro to T4 and T3; recovery from this effect did not occur by 120 min after oral administration of glucose. Calmodulin responsiveness of the enzyme in vitro was less significantly reduced in red cells obtained after glucose ingestion. Intravenous (i.v.) glucose administration (20 g) to five subjects also led to decreased basal enzyme activity (61% of fasting level at 20 min). A significant decrease in response of enzyme to T4 was achieved by 8 min after glucose administration (P less than 0.02), with recovery by 60 min.(ABSTRACT TRUNCATED AT 250 WORDS)
为了描述人类红细胞膜Ca2+-ATP酶(“钙泵”)活性的内源性调控机制,我们研究了生理范围内体内血糖浓度变化对红细胞中Ca2+-ATP酶活性的影响。我们还研究了在诱导高血糖过程中获得的红细胞,以确定膜Ca2+-ATP酶在体外对甲状腺激素和钙调蛋白刺激的敏感性,这两种物质先前已被证明可增强Ca2+-ATP酶活性。给8名健康成年受试者口服葡萄糖(75克)可导致血糖和免疫反应性胰岛素浓度出现可预测的升高。摄入葡萄糖后30分钟,红细胞中Ca2+-ATP酶的基础活性水平下降了55%(P<0.025),60分钟时酶活性恢复到与基础水平无显著差异。甲状腺素(T4,10(-10)M)、三碘-L-甲状腺原氨酸(T3,10(-10)M)和钙调蛋白(100纳克/毫克膜蛋白)在体外显著刺激零时红细胞Ca2+-ATP酶的活性。体内给予葡萄糖导致红细胞酶在体外对T4和T3的反应性降低;口服葡萄糖后120分钟这种效应仍未恢复。摄入葡萄糖后获得的红细胞中,该酶对钙调蛋白的反应性在体外降低的程度较小。给5名受试者静脉注射葡萄糖(20克)也导致基础酶活性降低(20分钟时为空腹水平的61%)。葡萄糖注射后8分钟,酶对T4的反应显著降低(P<0.02),60分钟时恢复。(摘要截短于250字)