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目的观察急、慢性代谢性酸中毒对大鼠红细胞外pH(pHe)和红细胞内pH(pHi)、碳酸酐酶(CA)和钠-氢交换蛋白Ⅰ(NHEⅠ)活性的影响。方法将24只Wistar大鼠随机分为急性组和慢性组。急性组又分为急性对照组和急性代谢性酸中毒组,慢性组又分为慢性对照组和慢性代谢性酸中毒组(n=6)。急性组采用静脉输注4mmol/kg-.1h-1HCl 4小时,慢性组采用0.28mmol/L NH4Cl喂饲7天,构建大鼠急性和慢性代谢性酸中毒模型;对照组分别给予等量0.9%生理盐水。分别于急性组0小时、2小时和4小时,慢性组0天、1天、3天、5天和7天抽取鼠尾静脉血0.5ml,肝素抗凝后测定血气分析。根据Wilbur等方法测定大鼠红细胞CA活性;通过激光共聚焦镜检,应用H+离子荧光探针(BCECF-AM)染色,观察红细胞内pH值变化;通过细胞酸化后细胞内pH值的恢复速率检测各条件下细胞膜上NHEⅠ功能的改变。结果急性代谢性酸中毒时红细胞NHEⅠ活性下降(P<0.05),但pHi和CA无明显变化;慢性代谢性酸中毒早期,红细胞pHi、NHEⅠ和CA活性无明显变化,但随着酸中毒的加重,第5天时红细胞CA和NHEⅠ的活性均明显增高(P<0.05),红细胞pHi下降(P<0.05)。结论急性代谢性酸中毒时,红细胞NHEⅠ活性下降,但红细胞pHi和CA活性并没有发生明显改变;慢性代谢性酸中毒可显著影响大鼠红细胞pHi、CA和NHEⅠ的活性。
Objective To observe the effects of acute and chronic metabolic acidosis on the activity of erythrocyte extracellular pH (pHe) and erythrocyte pHi, carbonic anhydrase (CA) and sodium-hydrogen exchange protein Ⅰ (NHEⅠ) in rats. Methods Twenty-four Wistar rats were randomly divided into acute group and chronic group. The acute group was divided into acute control group and acute metabolic acidosis group. Chronic group was divided into chronic control group and chronic metabolic acidosis group (n = 6). Acute and chronic metabolic acidosis model rats were established by intravenous infusion of 4mmol / kg-1h-1HCl for 4 hours in acute group and chronic group with 0.28mmol / L NH4Cl for 7 days in chronic group. The control group were given 0.9% Physiological saline. 0.5 ml of tail vein blood was drawn at 0, 2 and 4 hours in acute group, and 0, 1, 3, 5 and 7 days in chronic group. Blood gas analysis was performed after heparin anticoagulation. The activity of erythrocyte CA was measured by the method of Wilbur et al. The change of intracellular pH value was observed by laser scanning confocal microscopy with the H + ion fluorescent probe (BCECF-AM). The rate of recovery of intracellular pH Changes of NHE I function in cell membrane under various conditions. Results When acute metabolic acidosis, the activity of NHEⅠin erythrocytes decreased (P <0.05), but there was no obvious change in pHi and CA. At the early stage of chronic metabolic acidosis, the activity of pHi, NHEⅠand CA in erythrocytes had no significant changes. However, with the increase of acidosis On day 5, the activities of erythrocyte CA and NHEⅠwere significantly increased (P <0.05), and the erythrocyte pHi was decreased (P <0.05). Conclusions In acute metabolic acidosis, the activity of NHEⅠin erythrocytes decreased, but the pHi and CA activity of erythrocytes did not change significantly. Chronic metabolic acidosis could significantly affect the activity of pHi, CA and NHEⅠ in rat erythrocytes.