No abstract

Hydrogen sulfide exists widely in mammalian tissues and plays a vital role in physiological and pathophysiological processes. However, striking differences with orders of magnitude were observed for the detected hydrogen sulfide concentrations in biological matrices among different measurements in literature, which lead to the uncertainty for examination the biological relevance of hydrogen sulfide. Here, we developed and validated a liquid chromatography- mass spectrometry (LC-MS/MS) method for the determination of hydrogen sulfide in various biological matrices by determination of a derivative of hydrogen sulfide and monobromobimane named sulfide dibimane (SDB). 36S-labeled SDB was synthesized and validated for using as an internal standard. This method has been successfully used to measure hydrogen sulfide levels in a broad range of biological matrices, such as blood, plasma, tissues, cells, and enzymes, across different species. Moreover, a novel mode that hydrogen sulfide could loosely and non-covalently bind to human serum protein (HSA) and hemoglobin (HB) was revealed by using the developed method.

The absorption and transport mechanisms of berberine, palmatine, jateorhizine, and coptisine were studied using a Caco-2 cells uptake and transport model, with the addition of cyclosporin A and verapamil as P-glycoprotein (P-gp) inhibitors and MK-571 as a multidrug resistance-associated protein 2 (MRP(2)) inhibitor. In the uptake experiment, berberine, palmatine, jateorhizine, and coptisine were all taken into Caco-2 cells, and their uptakes were increased in the presence of cyclosporin A or verapamil. In the transport experiment, P(app) (AP-BL) was between 0.1 and 1.0 × 10(6) cm/sec for berberine, palmatine, jateorhizine, and coptisine and was lower than P(app) (BL-AB). ER values were all >2. Cyclosporin A and verapamil both increased P(app) (AP-BL) but decreased P(app) (BL-AB) for berberine, palmatine, jateorhizine, and coptisine; ER values were decreased by >50%. MK-571 had no influence on the transmembrane transport of berberine, palmatine, jateorhizine, and coptisine. At a concentration of 1-100 μM, berberine, palmatine, jateorhizine, and coptisine had no significant effects on the bidirection transport of Rho123. Berberine, palmatine, jateorhizine, and coptisine were all P-gp substrates; and at the range of 1-100 μM, berberine, palmatine, jateorhizine, and coptisine had no inhibitory effects on P-gp.