Assessment of absorption of four lignan constituents of JingNing particles in rat gut using in situ single-pass intestinal perfusion

Purpose: To study small intestinal absorption of schisadrol A, schisandrol B, schizandrin A and schisandrin B in JingNing particles using in situ single-pass intestinal perfusion (SPIP).Methods: Absorption rate constant (Ka) and apparent permeability (Papp) of the drugs at different concentrations in various parts of rat small intestine (duodenum, jejunum and ileum) were determined using SPIP. JingNing particles were also perfused in situ at different pH in the entire rat intestine. Ethanol extract of Schisandra chinensis (standard) at low concentration was perfused in the duodenum for comparison with extract of JingNing particles.Results: The order of apparent permeability of the four lignans was schisandrol A < schisandrol B < schizandrin A < schisandrin B. Ka and Papp values of the four lignans in JingNing particles were concentration-dependent. Absorption increased in the rank order: ileum > duodenum > jejunum. Optimum absorption pH was 6.50. Polygala tenuifolia extract and volatile oil of Rhizoma acori tatarinowii significantly (p < 0.05) enhanced the absorption of the four lignans.Conclusion: The four lignans were well absorbed in the intestinal tract, particularly the ileum, probably through carrier-mediated transport. The alcohol extract of Polygala tenuifolia and volatile oil of Rhizoma acori graminei enhanced the absorption of the four lignans.Keywords: JingNing, Intestinal absorption, Polygala tenuifolia, Rhizoma acori graminei, Lignans, Schisandrol, Schisandrin, Single-pass intestinal perfusio

Ionospheric modulation by EMIC wave-driven proton precipitation:observations and simulations

Abstract Protons of tens of keV can be resonantly scattered by electromagnetic ion cyclotron (EMIC) waves excited in the magnetosphere, resulting in proton precipitation down to the upper atmosphere. In this study, we report for the first time the ionospheric height-dependent ionization in response to EMIC-associated isolated proton aurora (IPA) using simultaneous space-borne and ground-based measurements. On 06 March 2019, the Polar Orbiting Environmental Satellites observed significant proton precipitation in the dusk sector (MLT ∼ 19), while ground-based magnetometers detected a clear signature of EMIC waves. Meanwhile, the conjugated all sky imager captured an IPA and the nearby Poker Flat incoherent scatter radar (PFISR) showed enhanced electron density in the E region, suggesting a potential consequence of the EMIC wave-driven proton precipitation. The Global Airglow model simulations confirmed the dominant impact of proton precipitation on the ionosphere and agreed well with PFISR observations. This study confirmed physical links from the magnetosphere to the ionosphere through EMIC-driven proton precipitation