Absorption characteristic of Paeoniflorin-6＇O-benzene sulfonate in an situ single-pass intestinal perfusion model

Aim Paeoniflorin-6＇O-benzene sulfonate （CP-25） was synthesized to improve oral absorption. This study was performed to investigate absorptive behavior and mechanism of CP-25 in intestine. Methods The effects of drug concentration, intestinal segments, gender as well as ATP binding cassette （ABC） transporter inhibitors on absorption of CP-25 were studied in a situ single-pass intestinal perfusion rat model. Meanwhile, Paeoniflorin （Pae） was tested and served as control group. The concentration of tested drugs was measured by HPLC. Results The results showed intestinal absorption of CP-25 was neither segmental dependent changes nor gender difference. Transepithelial transportation would not change with increasing concentrations of CP-25, which suggest a passive transport was the main pattern of CP-25. Additionally, absorption of CP-25 was much better than that of Pae in small intestine. When compared with Pae, CP-25 gave a 1.82-fold permeability rate. Finally, the results indicated Pae was substrate of P-glycoprotein （P-gp） , but was not the substrate of breast cancer resistance protein and muhi- drug resistance associated protein 2. Among the used ABC inhibitors, the absorption rate of Pae could only be in- creased by？ P-gp inhibitor Verapamil and GF120918, while CP-25 had no remarkable alteration. Conclusion CP-25 has better absorptive features than that of Pae, which may be attributed to its lipophicity enhancement and be unaffected by P-gp efflux.

In vivo perfusion staining of atherosclerotic lesions and a novel quantification method for lesion size in sequential aortic root sectioning in murine models

Objectives To develop a simple, accurate and reproducible method, which combines macro and histopathological techniques for determining the degree of lipid deposition in genetically modified mice. Method The entire aortas from C57BL/6, ldlr-/- and apoE-/- mice were stained with Sudan IV using either in vivo perfusion or traditional in vitro enface staining techniques. Histological sections of aortic root and hearts were embedded in tissue freezing medium and cut with a cryostat, then stained with Oil Red O. The calculated aortic root area based on the aortic root circumference was used to reduce measurement errors. Results The in vitro en face staining can stain all fat, which include the adventitial tissue around aorta. However the in vivo perfusion staining can specifically stain the fatty deposition inside of aorta. Both entire aorta and aortic root section staining showed that there was a highly significant increase in fatty deposition in the aortas of the genetic modified mice. Although all mice genetic background was same, the apoE-/- mice had larger atherosclerotic lesions than ldlr-/- mice. Conclusions The new in vivo peffusion method is more accurate than the in vitro en face method. The combination of these macro and microscopic techniques overcomes the shortcomings of the earlier published methods which are generally limited to the measurement of fatty red staining areas only, neglecting non-specific adventitial fat staining around aorta and aortic root section tissue distortion.