Zhi-Bi Hu

Effect of jatrorrhizine on delayed gastrointestinal transit in rat postoperative ileus.

Objectives  Postoperative ileus is major cause of postoperative complication and prolonged hospitalization. Jatrorrhizine, which is a protoberberine alkaloid isolated from the medicinal plants Berberis aristata and Coptis chinensis, has been found to increase contractility of gastric antral and ileum smooth muscles of rat gastrointestinal tract. We have investigated whether jatrorrhizine could offset gastrointestinal transit in rat with postoperative ileus.

Palmatine, a protoberberine alkaloid, inhibits both Ca2+‐ and cAMP‐activated Cl− secretion in isolated rat distal colon

The protoberberine alkaloid berberine has been reported to inhibit colonic Cl− secretion. However, it is not known if other protoberberine alkaloids share these effects. We have therefore selected another protoberberine alkaloid, palmatine, to assess its effects on active ion transport across rat colonic epithelium.

Gastroprotective effect of fructus evodiae water extract on ethanol-induced gastric lesions in rats.

Fructus Evodiae is a widely used herbal medicine with anti-inflammatory and analgetic activities in China. The present study was designed to investigate the effect of Fructus Evodiae water extract (FE) on ethanol-induced gastric lesions in rats. Three hours before ethanol challenge, animals were intraperitoneally treated with FE (424.8 mg/kg, 141.6 mg/kg, and 47.6 mg/kg). Subsequently, we employed ex-vivo chamber technique to examine the effect of FE on gastric transmucosal potential difference (PD) changes. NO(x) (nitrate and nitrite) in gastric perfusate and gastric lesion index of whole glandular stomach were determined by intubation. The results showed that FE dose-dependently accelerated the recovery of PD reduction by ethanol, and increased NO(x) production in gastric perfusate. FE also inhibited gastric lesion formation in a dose-dependent manner. These results suggested that FE prevented ethanol-induced gastric mucosal lesions by strengthening the mucosal barrier integrity and increasing gastric mucosal nitric oxide (NO) synthesis.

Traditional Chinese formula, lubricating gut pill, stimulates cAMP-dependent Cl− secretion across rat distal colonic mucosa

AIM OF THE STUDY Lubricating gut pill (LGP), a traditional Chinese formula, had been conformed to improve the loperamide-induced rat constipation by stimulation of Cl(-) secretion, but its mechanism has not been fully explored. Thus, the purpose of this study was to identify the action sites of LGP-stimulated Cl(-) secretion across rat distal colonic mucosa. MATERIALS AND METHODS Rat distal colonic mucosa was mounted in Ussing chambers and short circuit current (I(SC)), apical Cl(-) current and basolateral K(+) current were recorded. Intracellular cyclic adenosine monophosphate (cAMP) content and protein kinase A (PKA) activity were determined with ELISA kit and the non-radioactive PepTag test, respectively. RESULTS LGP at 800μg/ml elicited a sustained increase in Cl(-) secretory response, which was inhibited by CFTR(inh)172, a cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor. Permeabilizing apical membrane with nystatin revealed that LGP-stimulated basolateral K(+) current was significantly inhibited by KCNQ1 K(+) channel inhibitor chromanol 293B. LGP-stimulated I(SC) was markedly reduced by pretreatment with cis-N-[2-phenylcyclopentyl]-azacyclotridec-1-en-2amine (MDL-12,330A) and N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), but not with inhibitors of Ca(2+)-dependent signaling pathway. Treatment of tissue with LGP resulted in an increase in intracellular cAMP level and the activation in protein kinase A. The E-prostanoid(4) (EP)(4) receptor antagonist L-161,982 completely eliminated LGP-induced response. CONCLUSIONS The results showed that LGP enhances Cl(-) and fluid secretion via prostanoid receptor signaling and also cAMP and protein kinase A pathway, subsequently triggering the activation of apical Cl(-) channels mostly CFTR and basolateral cAMP-dependent K(+) channel.

The effects of jatrorrhizine on contractile responses of rat ileum.

This study was designed to evaluate the effect of jatrorrhizine on smooth muscle contractions isolated from rat ileum longitudinal muscles. Jatrorrhizine increased the amplitude of spontaneous contractions of ileum longitudinal muscles in concentration-dependent manner with an EC(50) of 30.0±8.4μM. Preincubation of ileum strips with atropine (1μM), 4-diphenyllacetoxy-N (2-chloriethyl)-piperidine (4-DAMP, 1μM) or darifenacin (1μM) significantly inhibited acetylcholine (0.1μM)- and jatrorrhizine (100μM)-induced ileum longitudinal muscle contractions, whereas they were not affected by AF-DX116 (1μM) or hexamethonium (100μM). Pretreatment with SB204070 (1μM) rather than 3-tropanyl-indole-3-carboxyleat (tropisetron, 1μM) significantly inhibited 5-HT (10μM)-induced ileum longitudinal muscle contractions. In contrast, jatrorrhizine-induced ileum longitudinal muscle contractions were not inhibited by tropisetron or SB204070. Furthermore, jatrorrhizine-induced ileum longitudinal muscle contractions were strongly inhibited by nifedipine (1μM), and also attenuated by removal of extracellular Ca(2+), U73122 (1μM), ruthenium red (50μM) or 2-aminoethoxydiphenylborate (2-APB, 10μM). Taken together, jatrorrhizine-elicited spontaneous contractions in rat ileum longitudinal muscles are mediated by activation of acetylcholine receptors, mostly the M(3) receptor. Ca(2+) influx through L-type Ca(2+) channel is significantly contributed to jatrorrhizine-elicited spontaneous contractions, and Ca(2+) release via IP(3) and ryanodine pathways are also involved.

Metabolic responses induced by thrombin in human umbilical vein endothelial cells.

Metabolic responses induced by thrombin in human umbilical vein endothelial cells (HUVECs) were investigated by using the cytosensor technique. Thrombin increased the extracellular acidification rate of endothelial cells, measured as an index of metabolic activity with a cytosensor microphysiometer, in a concentration-dependent fashion with an EC(50) of 1.27+/-0.59 IU/ml, which was abolished by the MAP kinase inhibitor PD98059. When intracellular Ca(2+) was chelated or PKC was inactivated, PD98059 failed to abolish the thrombin-induced acidification rate response in HUVECs. In addition, the tyrosine kinase inhibitor genistein, PKC inhibitor calphostin C, and Na(+)/H(+)exchanger antagonist MIA also partly inhibited thrombin-induced acidification rate responses. It is suggested that thrombin stimulated rapid metabolic responses via MAP kinase in HUVECs, which are calcium- and PKC-dependent.

Traditional Chinese formula, lubricating gut pill, improves loperamide-induced rat constipation involved in enhance of Cl− secretion across distal colonic epithelium

AIM OF THE STUDY Lubricating gut pill (LGP), a traditional Chinese formula, was widely used for the treatment of chronic constipation, especially in the elderly, in China. However, it is unclear whether LGP-induced laxative and/or lubricating effect is involved in water and electrolytes transport in distal colonic epithelium. MATERIALS AND METHODS The present study was designed to evaluate the effect of LGP on Cl(-) secretion across rat distal colonic epithelium mounted in Ussing chambers, and on a rat constipation model induced by loperamide, respectively. RESULTS Application of LGP in the apical side elicited a sustained increase in short circuit current (I(SC)) response in a concentration-dependent manner. Evidence that LGP-stimulated I(SC) was due to Cl(-) secretion is based on inhibition of current by (a) a Na(+)-K(+)-2Cl(-) cotransporter inhibitor bumetanide, (b) removal of Cl(-) ions in bath solution, and (c) the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel blocker DPC, suggesting that a apical cAMP-dependent Cl(-) channel was activated. LGP-stimulated I(SC) was also strongly inhibited by pretreatment with clotrimazole, indicating that the basolateral K(+) channel was also involved in maintaining this cAMP-dependent Cl(-) secretion. Pretreatment of tissues with indomethacin, but not atropine, tetrodotoxin or hexamethonium, inhibited LGP-induced response. In a rat constipation model, oral administration with LGP was significantly restored number of fecal pellets, water content and mucus secretion compared with loperamide-treated group alone. CONCLUSIONS LGP enhances Cl(-) secretion that is mostly mediated through the release of cyclooxygenase metabolites, by which provided an osmotic force for the subsequent laxative action observed in the rat constipation model.