Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, CCM, Tucholskystr. 2, D-10117 Berlin, Germany.
Radiology. 2010 Aug;256(2):406-14. doi: 10.1148/radiol.10091485. Epub 2010 Jun 7.
To compare changes in urinary viscosity in the renal tubules following administration of a high-viscosity iso-osmolar contrast agent (iodixanol) to that observed following administration of a less viscous, higher osmolar contrast agent (iopromide) in anesthetized rats.
A total of 43 rats were studied. Experiments were approved by the Berlin, Germany, animal protection administration. A viscometer was developed to measure viscosity in minute samples (7 microL). Urine was collected, viscosity was measured (at 37 degrees C), and glomerular filtration rate (GFR) was determined by means of creatinine clearance. Boluses of 1.5 mL of iodixanol (320 mg iodine per milliliter, iso-osmolar to plasma, high viscosity) or iopromide (370 mg iodine per milliliter, higher osmolality and lower viscosity than iodixanol) were injected into the thoracic aorta. There were five groups (seven rats per group). Groups 1 (iodixanol) and 2 (iopromide) had free access to water prior to the experiment; groups 3 (iodixanol) and 4 (iopromide) received an additional infusion of isotonic saline (4 mL/kg/h). Group 5 was treated as group 1 but received only 0.75 mL of iodixanol. The observation period was 100 minutes. Statistical comparisons were made by means of nonparametric procedures (Friedman test, Kruskal-Wallis test).
Iodixanol increased urine viscosity from 0.69 to 36.7 mm(2)/sec; thus, urine became threefold more viscous than native iodixanol solution. The increase in urine viscosity after injection of iopromide was from 0.73 to 2.3 mm(2)/sec. While GFR was not significantly affected by iopromide, GFR transiently decreased by 50% after administration of iodixanol. Iopromide had a diuretic effect twofold greater than that of iodixanol. Saline infusion blunted the viscosity rise and transient decline in GFR caused by iodixanol, as did reducing the iodixanol dose by 50%.
Contrast media, in particular iodixanol, increase urine viscosity (which is equal to tubular fluid viscosity in the collecting ducts); in response to iodixanol, GFR markedly decreases. Saline infusion attenuates this response, thus potentially explaining the protective effects of volume expansion in contrast medium-induced nephropathy.
比较高粘度等渗造影剂（碘昔醇）和低粘度高渗造影剂（碘普罗胺）给药后肾小管尿粘度的变化。
共研究了 43 只大鼠。实验得到了德国柏林动物保护管理局的批准。开发了一种粘度计来测量微样本（7 μL）的粘度。收集尿液，测量粘度（37°C），并通过肌酐清除率测定肾小球滤过率（GFR）。将 1.5 mL 碘昔醇（320 mg 碘/毫升，与血浆等渗，高粘度）或碘普罗胺（370 mg 碘/毫升，比碘昔醇高渗透压和低粘度）的推注注入胸主动脉。有 5 组（每组 7 只大鼠）。第 1 组（碘昔醇）和第 2 组（碘普罗胺）在实验前可自由饮水；第 3 组（碘昔醇）和第 4 组（碘普罗胺）接受等渗盐水（4 mL/kg/h）额外输注。第 5 组作为第 1 组治疗，但仅接受 0.75 mL 碘昔醇。观察期为 100 分钟。统计比较采用非参数程序（Friedman 检验，Kruskal-Wallis 检验）进行。
碘昔醇使尿液粘度从 0.69 增加到 36.7 mm²/sec，使尿液的粘度比天然碘昔醇溶液增加了三倍。注射碘普罗胺后尿液粘度从 0.73 增加到 2.3 mm²/sec。虽然碘普罗胺对 GFR 没有显著影响，但碘昔醇给药后 GFR 短暂下降 50%。碘普罗胺的利尿作用是碘昔醇的两倍。盐水输注可减轻碘昔醇引起的粘度升高和 GFR 短暂下降，减少碘昔醇剂量 50%也可减轻这种反应。
造影剂，特别是碘昔醇，会增加尿液粘度（与集合管中的管状液体粘度相等）；碘昔醇会导致 GFR 明显下降。盐水输注可减轻这种反应，因此可能解释了在造影剂引起的肾病中扩容的保护作用。
