BACKGROUND:The gallbladder filling and emptying cycle controls bile flow into the duodenum. Disruption of this emptying and refilling cycle leads to bile stasis and subsequent gallstone formation. The bile flow rate is inversely proportional to its viscosity. Moreover, bile is a complex material with varying density in different people because of its diverse components. These density changes alter the viscosity. Prediction of shear viscosity from density measurements may thus contribute to medical assessment and treatment of the patient. OBJECTIVE:To investigate the relationship between the shear viscosity and density of bile. METHODS:Natural and filtered bile samples were prepared for density, viscosity and pressure drop measurements. The density and shear viscosity were measured by a density meter and viscometer, respectively, and a relationship was established between them. Measurements of the pressure drop in a glass tube were used to estimate the apparent viscosity and compared with shear viscosity obtained with the viscometer. RESULTS:The natural bile with higher density showed a greater shear viscosity than the filtered bile, especially at low shear rates. Bile viscosity was proportional to density. In addition, the pressure drop of the natural samples was greater than that of the filtered sample. The viscosity measured by the viscometer deviated from the results obtained using Poiseuille’s law and the tube pressure drop measurements. The density difference between the natural and filtered bile samples was smaller than 1%. However, the viscosities of the natural and filtered bile samples varied by up to >30%. CONCLUSIONS:Porcine bile viscosity is proportional to density. Based on the bile density, one can easily evaluate the shear viscosity using a linear relationship. The density considerably influences the bile viscosity, with small density increases greatly increasing the shear viscosity.

中文翻译：

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猪胆汁的粘度与密度成正比。

背景：胆囊填充和排空周期控制胆汁流入十二指肠。排空和再填充周期的中断会导致胆汁淤滞和随后的胆结石形成。胆汁流速与其粘度成反比。此外，胆汁是一种复杂的材料，由于其成分多样，因此在不同的人群中密度会有所不同。这些密度变化会改变粘度。因此，根据密度测量值预测剪切粘度可有助于医学评估和患者治疗。目的：探讨剪切粘度与胆汁密度的关系。方法：制备天然和过滤胆汁样品以进行密度，粘度和压降测量。密度和剪切粘度分别通过密度计和粘度计测量，他们之间建立了联系。使用玻璃管中的压降测量来估计表观粘度，并将其与用粘度计获得的剪切粘度进行比较。结果：密度较高的天然胆汁比过滤后的胆汁具有更高的剪切粘度，尤其是在低剪切速率下。胆汁粘度与密度成正比。另外，天然样品的压降大于过滤样品的压降。粘度计测得的粘度与使用泊厄依耶定律和管压降测量所得的结果不同。天然和过滤后的胆汁样品之间的密度差小于1％。但是，天然胆汁和过滤后胆汁样品的粘度变化高达> 30％。结论：猪胆汁的粘度与密度成正比。基于胆汁密度，可以使用线性关系轻松评估剪切粘度。密度极大地影响了胆汁的粘度，密度越小，胆汁粘度的增加就越大。