Liu S Q, Fung Y C
Department of Applied Mechanics and Engineering Sciences/Bioengineering, University of California, San Diego 92093-0412.
Diabetes. 1992 Feb;41(2):136-46. doi: 10.2337/diab.41.2.136.
Zero-stress states of the main pulmonary arteries and aorta and small systemic arteries were determined in 22 nondiabetic and 29 streptozocin (STZ)-induced diabetic rats. The zero-stress state of each vessel was obtained by cutting the vessel transversely into a series of short rings, then cutting each ring radially, which caused the ring to spring open into a sector. Each sector can be characterized by its opening angle. The opening angle has strong regional dependence. In some regions of rat arteries, the opening angle can be greater than 360 degrees. Rats were studied 5, 10, 20, 30, and 40 days after an injection of 75 mg/kg body wt i.v. STZ. During diabetes development, the opening angles in general increased and reached a plateau in approximately 30 days. The maximum change of opening angle over normal lies in the range of 18-105 degrees, depending on location. The pulmonary arteries were affected by diabetes as much as the systemic arteries. The course of change of the opening angle during diabetogenesis was different from those of the serum glucose level and blood pressure. Blood pressure in carotid, external iliac, and pulmonary arteries did not change significantly in diabetogenesis. To clarify the physiological meaning of the opening angle, we measured the circumferential strain in the blood vessel wall in homeostatic condition and the residual strain at the no-load state, with both strains referred to the zero-stress state. We calculated the corresponding stresses in the vessel wall. The circumferential stress in the vessel wall was greatly increased by diabetes; great errors will result if the opening angle is ignored.
在22只非糖尿病大鼠和29只链脲佐菌素（STZ）诱导的糖尿病大鼠中测定了主肺动脉、主动脉和小体循环动脉的零应力状态。通过将血管横向切成一系列短环，然后沿径向切割每个环，使环弹开成扇形，从而获得每个血管的零应力状态。每个扇形可以用其张开角度来表征。张开角度具有很强的区域依赖性。在大鼠动脉的某些区域，张开角度可以大于360度。在静脉注射75mg/kg体重的STZ后5、10、20、30和40天对大鼠进行研究。在糖尿病发展过程中，张开角度总体上增加，并在大约30天达到平台期。张开角度相对于正常的最大变化范围在18 - 105度之间，具体取决于位置。肺动脉和体循环动脉受糖尿病影响的程度相同。糖尿病发生过程中张开角度的变化过程与血糖水平和血压的变化过程不同。在糖尿病发生过程中，颈动脉、髂外动脉和肺动脉的血压没有显著变化。为了阐明张开角度的生理意义，我们在稳态条件下测量了血管壁的周向应变和空载状态下的残余应变，这两种应变均相对于零应力状态。我们计算了血管壁中的相应应力。糖尿病会使血管壁中的周向应力大大增加；如果忽略张开角度，将会导致很大的误差。
