OBJECTIVETo explore the correlation between Pi and Shen by observing the relationship between the metabolism of aristolochic acid (AA) and mRNA and protein expression levels of organic anion transporting polypeptide (oatp) superfamily member 2a1 and 2 b1 (oatp2al and oatp2bl) in renal, small intestinal, and large intestinal tissues of Pi deficiency syndrome (PDS) model rats.

METHODSTotally 46 Sprague-Dawley (SD) rats were randomly divided into four groups, i.e., the blank group (n = 12), the PDS group (n = 22), the AA-I group (n = 6), and the PDS AA-I group (n = 6). PDS model was established by subcutaneously injecting Reserpine at the daily dose of 5 mg/kg for 16 successive days. Carotid intubation was performed in 6 rats selected from the blank group and the PDS group. Pharmacokinetics of AA-I were detected at 5, 15, 30, 45, and 60 min after gastrogavage of AA-I. AA-I concentrations in renal, small intestinal, and large intestinal tissues of 10 rats selected from the PDS group were determined. Normal saline was administered to 6 rats selected from the PDS group and the blank group by gastrogavage. Renal, small intestinal, and large intestinal tissues were collected in the AA-I group and the PDS AA-I group at 60 min after gastrogavage of AA-I. mRNA and protein expression levels of oatp2a1 and oatp2b1 in each tissue were detected using real-time polymerase chain reaction (RT- PCR) and Western blot.

RESULTSCompared with the blank group, plasma concentrations of in vivo AA-I were obviously higher in the PDS group at 15, 30, 45, and 60 min after gastrogavage of AA-I with statistical difference (P < 0.05). Plasma concentrations of AA-I were obviously decreased at 60 min after gastrogavage of AA-I; AA-I concentrations in renal and large intestinal tissues were elevated; AA-I concentrations in small intestinal tissues were obviously reduced in the PDS group. There was no statistical difference in mRNA expression levels of oatp2a1 and oatp2b1 in the aforesaid three tissues of rats between the blank group and the PDS group. Compared with the blank group, mRNA expression levels of oatp2a1 and oatp2b1 decreased in small intestinal tissues of the AA-I group, and the mRNA expression level of oatp2a1 in large intestinal tissues significantly decreased (P < 0.05, P < 0.01). Compared with the PDS group, mRNA expression levels of oatp2a1 and oatp2b1 increased in renal tissues of the PDS AA-I group (P < 0.05); mRNA expression levels of oatp2b1 increased in large intestinal tissues of the PDS AA-I group (P < 0.05).

CONCLUSIONSThe difference in AA-I metabolism might be associated with changed expression levels of oatp2a1 and oatp2b1 in renal, small intestinal, and large intestinal tissues under Pi deficiency induced loss of transportation. Shen and Dachang played important roles in substance metabolism under Pi deficiency state, which proved Pi-Shen correlated in Chinese medical theories.