Nymark Soile, Haldin Charlotte, Tenhu Heikki, Koskelainen Ari
Laboratory of Biomedical Engineering, Helsinki University of Technology, Espoo, Finland.
Invest Ophthalmol Vis Sci. 2006 Jun;47(6):2583-8. doi: 10.1167/iovs.05-1116.
To develop a method of using isolated rat retina as a biosensor in experiments on controlled drug release for measuring the resultant concentration of free model drug in living tissue and for testing the biocompatibility of the polymers and polymeric nanostructures used as drug carriers.
The method is based on the monotonic dependence of the photoresponse kinetics of retinal rods on the concentration of the membrane-permeable phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Changes in the time to peak (tp) of linear-range rod photoresponses were followed by transretinal ERG mass potential recordings in the aspartate-treated, dark-adapted rat retina. The dependence of tp on [IBMX] was measured, and the calibration curve thus obtained was used to determine the amount of IBMX released from polymeric structures. The biocompatibility of the carrier was first assessed by the degree to which rods retained stable function in the presence of the polymer or monomers alone.
The dependence of tp on [IBMX] was well-described by a second-order polynomial. After each change of [IBMX], a new equilibrium state was reached within 6 to 9 minutes, depending on temperature. The amounts of IBMX released from biocompatible polymeric structures were measurable with good accuracy in the range 10 to 300 microM.
This method enables accurate concentration determinations of the model drug IBMX in retinal tissue in drug-release experiments. The concentration dependence of the photoresponse kinetics has to be calibrated for each retina and temperature. The same preparation can be used for rapid testing of possible bioincompatibility of various molecules.
开发一种利用分离的大鼠视网膜作为生物传感器进行控释药物实验的方法，以测量活组织中游离模型药物的最终浓度，并测试用作药物载体的聚合物和聚合物纳米结构的生物相容性。
该方法基于视网膜视杆细胞光反应动力学对膜通透性磷酸二酯酶抑制剂3 - 异丁基 - 1 - 甲基黄嘌呤（IBMX）浓度的单调依赖性。在天冬氨酸处理的暗适应大鼠视网膜中，通过经视网膜ERG质量电位记录跟踪线性范围视杆细胞光反应的峰值时间（tp）变化。测量tp对[IBMX]的依赖性，并使用由此获得的校准曲线来确定从聚合物结构中释放的IBMX量。首先通过视杆细胞在仅存在聚合物或单体的情况下保持稳定功能的程度来评估载体的生物相容性。
tp对[IBMX]的依赖性可用二阶多项式很好地描述。每次[IBMX]变化后，根据温度在6至9分钟内达到新的平衡状态。从生物相容性聚合物结构中释放的IBMX量在10至300 microM范围内可准确测量。
该方法能够在药物释放实验中准确测定视网膜组织中模型药物IBMX的浓度。光反应动力学的浓度依赖性必须针对每个视网膜和温度进行校准。相同的制剂可用于快速测试各种分子可能的生物不相容性。
