采用微渗透泵测定清醒大鼠肾小球滤过率

Determination of Glomerular Filtration Rate Using Micro-osmotic Pump in Conscious Rat

目的分析以荧光素异硫氰酸酯标记的菊粉(FITC-菊粉)作为标记物,通过微渗透泵,在大鼠清醒状态下,采用菊粉尿排泄率方法测定肾小球滤过率的可行性。方法将FITC-菊粉溶解在生理盐水中配成浓度为24%的溶液,经滤过后(浓度降至8%)装在微渗透泵内。大鼠腹腔植入2个盛有上述FITC-菊粉溶液的微渗透泵,随机分成2组(需要收集24 h尿量组及无需收集尿量组每组各10只),分别关在代谢笼内。植泵后第7天,需要收集24 h尿量组收集24 h尿量及代谢笼上残留的FITC-菊粉,在大鼠清醒状态下采集血液标本;无需收集尿量组仅采集血液标本。分别根据不同的公式计算GFR。GFR的计量单位为mL/min,分别用大鼠体重及双肾重量校正后的单位为mL/min.kg体重和mL/min.g体重。结果需要收集24 h尿量和无需收集尿量2种方法计算出来的GFR分别为(2.31±0.33)mL/min和(2.53±0.33)mL/min,P=0.564,两者之间差异无统计学意义;与已发表文献相比大鼠GFR平均值3.24 mL/min降低了30%,说明麻醉对GFR有较明显影响,去除麻醉因素的影响后,两者数值相近。结论采用微渗透泵方法,用FITC-菊粉作为标记物,可以比较准确地测定清醒状态下大鼠GFR,尤其是无需收集尿量方法更加简便。

Objective Two non-radioactive methods for determining glomerular filtration rate （GFR） in conscious rat using FITC-labeled inulin （FITC-inulin） and micro-osmotic pumps were evaluated. Methods FITC-inulin （24%） was dissolved in 0.9% NaC1 and the concentration decreased to 8% after 24 h of dialysis. Two micro-osmotic pumps filled with 200 μL of 8% FITC-inulin were inserted into the peritoneal cavity of rats. After their complete recovery from anesthesia, the rats were housed individually in metabolic cages. Urine and the residual fluorescence remaining on the cages were collection over 24 h on day 7 after micro-osmotic pump implantation. Blood sample was collected through the saphenous vein at the end of 24-h urine collection. Only blood was sampled using the same method in another group. GFR was evaluated on day 7 after micro-osmotic pump implantation using two methods expressed in microliters per minute, microiiters per minute per kilogram body weight and per gram kidney weight. Results Based on the approach measuring urinary inulin clearance with urine collection and without urine collection the estimated GFR was （2. 31 ± 0. 33） microliters per minute and （2.53 ± 0. 33） mieroliters per minute （P = 0. 564） , respectively. These values of GFR in conscious rats were only ca. 70% of that obtained in anesthetized rats determined in other previous studies. It was revealed that anesthesia may significantly influence GFR. Conclusions The results of the present study demonstrate the feasibility of the osmotic micropump approach to monitor GFR in conscious rat using FITC-inulin. Especially, the method without collecting urine is more convenient.