Calcium channel blockade and anti-free-radical actions of panaxatriol saponins in cultured myocardiocytes.

AIM: To identify the calcium channel blockade and anti-free-radical actions of panaxatriol saponins Re, Rf, Rg1, Rg2, Rh1, and oleanolic acid saponin Ro. METHODS: On ventricular myocytes of Wistar rats, single channel activities of B, L, and T type calcium channels were recorded with the cell-attached configuration of patch-clamp technic, and free radical contents were measured with electron spin resenance method. RESULTS: Re, Rg1, Rg2, and Rh1 shortened the open times, prolonged the close times, and reduced the open-state probabilities of B, L, and T type calcium channels; Rf shortened the open time, prolonged the close time and reduced the open-state probability of L type calcium channel; Ro did not influence the activity of calcium channels (60 mumol.L-1). Re, Rg1, Rg2, and Rh1 antagonized the increase of free radical content induced by xanthine 0.42 mmol.L-1-xanthine oxidase 5.3 nmol.L-1; Ro and Rf had no effect (30 mumol.L-1). CONCLUSION: Re, Rg1, Rg2, and Rh1 had both the calcium channel blockade and antifree-radical actions. Rf had blockade action on L type calcium channel.

[Calcium channel blockade and anti-free-radical actions of panaxadiol saponins Rb1, Rb2, Rb3, Rc, and Rd].

AIM: To identify the calcium channel blockade and anti-free-radical actions of panaxadiol saponins Rb1, Rb2, Rb3, Rc, and Rd. METHODS: On ventricular myocardiocytes of Wistar rats, single channel activities of L, T, and B type Ca2+ channels were recorded with the cell-attached configuration of patch-clamp technic, and free radical contents were measured with electron spin resenance method. RESULTS: Rb1, Rb2, Rb3, and Rc 200 mumol.L-1 shortened the open times, prolonged the close times, and reduced the openstate probabilities of calcium channels and 30 mumol.L-1 antagonized the increase of free radical content induced by xanthine 0.42 mmol.L-1-xanthine oxidase 5.3 nmol.L-1, but Rd in the same dose behaved none of the effects. CONCLUSION: Rb1, Rb2, Rb3, and Rc had both the calcium channel blockade and anti-free-radical actions.

[Influence of the 2nd and 3rd grade abstracts from scorpion venom of Buthus martensii Karsch on action potentials of fast response myocardiocytes].

AIM: To screen the active components of sodium channel blockade action from Buthus martensii Karsch (BMK) scorpion venom. METHODS: Myocardiocytes of mice were cultured. Action potentials of fast response myocardiocytes were recorded. The effects of 22 contents of BMK scorpion venom in a concentration of 3 mg.L-1 were tested and compared with that of TTX 2.5 mg.L-1, nimodipine (Nim) 3 mg.L-1 and BaCl2 24.4 mg.L-1. RESULTS: BMK-1 and other 19 contents significantly decreased depolarization parameters Vmax, APA, OS, and MDP, which was similar to that of TTX and different from that of Nim and BaCl2. CONCLUSION: The variations in the action potentials of fast response myocardiolcytes indicated that 20 contents of BMK scorpion venom had sodium channel blockade action.

Shark fin enriched diet prevents mucosal lipid abnormalities in experimental acute colitis.

Marine lipids contain eicosapentaenoic acid (EPA) which has anti-inflammatory effects. The aim of this research was to study, using the dextran sulfate induced acute colitis (AC) model, the effect of an EPA-rich shark fin supplemented diet on the mucosal lipid composition. The histology score increased in AC (p < 0.05), but only slightly in the EPA group. Similarly, colonic permeability to a intraluminally instilled water-soluble contrast medium significantly increased in the AC group, but not in EPA group. As compared with controls, the AC group showed lower levels of phosphatidylethanolamine, phosphatidylinositol, free fatty acid C20:5, and PL-FA C18:1 and C18:2 and higher levels of sphingomyelin, lysophosphatidylcholine, and C18:1 and free fatty acid C20:4 (p < 0.01) after 2 and 7 days. In the EPA group sphinogmyelin and lysophosphatidylcholine slightly increased and free fatty acid C20:4 decreased (p < 0.05) after 7 days, and no PL-FA change occurred. This study confirms the protective properties of EPA-rich marine food. EPA-enriched diet is protecting the colonic mucosa from the early derangements of lipid components occurring in this experimental AC model. This effect is likely to contribute to maintain an effective mucosal lining barrier.

[Single calcium channel analysis and electron spin resonance (ESR) spectral study on the myocardial effects of ginsenoside Rb2].

Based on the patch clamp technique, the effect of ginsenoside Rb2 on the single channel activity of Ca2+ was observed through the single ventricular myocytes of Wistar rats. Electron spin resonance was used to measure the free radical contents of cultured cardiomyocytes. It is proved that Rb2 can inhibit the activities of single calcium channel and significantly antagonize the increase of free radical contents induced by xanthine-xanthine oxidase.

[Single channel analysis on calcium channel blockade action of panaxadiol and panaxatriol saponins on cultured rat ventricular myocytes].

Wistar rat ventricular myocytes were isolated. Panaxadiol saponins 1500 micrograms.ml-1, panaxatriol saponins 300 micrograms.ml-1, verapamil 37.5 micrograms.ml-1, or BAY k 8644 5 mumol.L-1 were added into the bath solution separately. The single channel activities of L, T, and B type calcium channels were recorded before and after the administration, using voltage patch-clamp technique in cell-attached configuration. The calcium channel blockade effect of these 2 groups of ginsenosides was authenticated verified. The mechanism existed in the decrease in both the open time and the open-state probability of the calcium channel.

[Influence of 11 ginsenoside monomers on action potentials of myocardiocytes].

Eleven ginsenoside monomers were added to cultured myocardiocytes of neonatal Wistar rats in a concentration of 20 micrograms.ml-1. And the action potentials (AP) were led with microelectrodes. Rb1, Rb2, Rb3, Rc, Rg1, Rg2, Re, and Rh1 inhibited AP, decreasing APA by 20%, 13%, 5%, 18%, 30%, 37%, 28%, and 23%, respectively. The potency of the most effective monomer Rg2 20 micrograms.ml-1 was similar to that of the calcium channel blocker nimodipine 1.25 micrograms.ml-1. Rd, Rf, and Ro had no significant influence on AP. The average potency of the panaxatriol saponin (PTS) monomers were greater than that of the panaxadiol saponin (PDS) monomers. The above demonstrate the reason why the calcium channel blockade action of PTS is stronger than that of PDS results from the summation of monomer drug effects.

[Sodium channel blocking effect of scorpion venom on cultured mouse myocardiocytes].

Myocardiocytes of mice were cultured. Action potentials were recorded with microelectrodes inside the cells. Scorpion venom from Buthus martensii Karsch 3.75 or 7.5 micrograms.ml-1 decreased the duration of action potential and all of the depolarization concerned parameters of myocardiocytes. The Vmax, TP, APA behaved apparently in a dosage-dependent way. Restoration happened after washing out. Tetrodotoxin 2.5 micrograms.ml-1 acted in a similar way. Nimodipine 3.0 micrograms.ml-1 led to a decrease in action potential duration. BaCl2 0.1 mmol.L-1 elongated the action potential duration, while decreased the parameters concerned with depolarization. These results indicate that the scorpion venom has Na+ channel blocking action.

[Antioxidative action of soyasaponin monomers I, A1, A2, and their inhibitory effects on action potential and beating of myocardiocytes in culture].

Ventricular myocardiocytes from newborn Wistar rats were cultured. Soyasaponin monomers I, A1, A2 2 micrograms.ml-1 added to the culture medium, like nimodipine 1.25 microgram.ml-1, decreased the number of spontaneously beating clusters and the action potential parameters of myocardiocytes, which restored after washing out and were reversed by Ca2+ 80 micrograms.ml-1 or epinephrine 10 micrograms.ml-1, indicating the Ca2+ channel blockade action of the saponin monomers. Adding xanthine 0.42 mmol.L-1 and xanthine oxidase 5.4 nmol.L-1 into culture medium led to the increase of free radical content of the myocardiocytes and the decrease of action potential parameters, which were reversed by I 2 micrograms.ml-1, indicating the antioxidative action of saponin monomer I.

[Anti-free-radical damaging action of panaxadiol saponins and panaxatriol saponins on the myocardial contractibility of the isolated rat working heart].

Rats were free-radical-damaged by xanthine 6.4 mg.100g-1.d-1 and xanthine oxidase 0.1U.100g-1d-1 to cause significant decrease in the cardiac functional parameters. Panaxatriol saponins 10mg.100g-1.d-1 converted all the indices toward normal without exception. Panaxadiol saponins were more effective than panaxatriol saponins.

Duodenal bicarbonate secretion induced by human epidermal growth factor in rats is partially mediated by prostaglandins.

In the present study, the effect of graded intravenous infusions of human epidermal growth factor (hEGF) 0.005, 0.05 and 0.25 micrograms/ml, with or without 4 mg/kg i.p. indomethacin pretreatment, on rat duodenal bicarbonate secretion was investigated. Perfused duodenal loops were prepared in rats which were given intravenous infusions of hEGF with or without indomethacin. Duodenal pH and pCO2 were measured at 5-min intervals for 45 min, and bicarbonate secretion was calculated. Compared to control, each dose of hEGF caused a significant dose/response rise of duodenal bicarbonate secretion. Prostaglandin release was abolished by indomethacin pretreatment. Indomethacin-pretreated rats had a significant reduction of bicarbonate secretion which was still higher than in controls. These results provide evidence that duodenal bicarbonate secretion induced by hEGF is only partly accounted for by a prostaglandin-dependent mechanism.

Influences of ginsenosides Rb1, Rb2, and Rb3 on electric and contractile activities of normal and damaged cultured myocardiocytes.

Free radical damage to the cultured myocardiocytes of Wistar rat was induced by adding xanthine 0.42 mmol.L-1 and xanthine oxidase 5.3 nmol.L-1 to the culture medium. 30 micrograms.ml-1 of Rb1, Rb2 or Rb3 extracted from the leaf and stem of Panax ginseng C A Meyer restored the action potentials (AP) of free radical damaged cells to normal, indicating their antioxidative action. On normal myocardial cells, Rb1, Rb2, Rb3 20 micrograms.ml-1 inhibited the AP and spontaneous contractility, (suggesting the Ca channel blockade action of panaxadiol saponins). The degrees of their inhibitory effects were found to be Rb1 > Rb2 > Rb3. Their effects against X-XO were basically the same.

Effects of copper and selenium on electric parameters of cultured myocardial cells damaged by xanthine-xanthine oxidase.

Addition of xanthine 0.42 mmol.L-1 and xanthine oxidase 5.3 nmol.L-1 (X-XO) to the culture medium increased the amplitude of ESR spectra of myocardial cells, demonstrating an increase in free radical contents; diminished the action potential parameters significantly and reduced the input impedances from 0.34 +/- 0.11 to 0.24 +/- 0.1 M omega, expressing a typical electrical appearance of membrane damage. Supplying Cu 62.5 ng.ml-1 and/or Se 173 ng.ml-1 to the medium brought all of the electric parameters and the free radical content of myocardial cells back to normal. The results indicate that both the two trace elements are able to scavenge free radicals, thus antagonizing X-XO, which induces damage to myocardial cells.

[Effects of panaxadiol and panaxatriol saponins on action potentials of normal and xanthine-xanthine oxidase damaged cultured myocardial cells].

Wistar rat myocardial cells were cultured. PDS 20-80 micrograms.ml-1; PTS 1.25-20 micrograms.ml-1 dose-dependently decreased their action potential parameters, indicating the possibility of being concerned in the blockage of Ca channel. After the free radical damage was induced by xanthine 0.42 mmol.L-1--xanthine oxidase 5.3 nmol.L-1 (X-XO). All the action potential parameters of the cardiac cells decreased without exception. Both PDA and PTS antagonized the electrical appearance of membrane damage induced by X-XO, suggesting that both PDS and PTS protect the myocardial cells from oxidative damage.

Protective action of selenium and manganese on xanthine and xanthine oxidase induced oxidative damage to cultured heart cells.

Ventricular myocytes from neonatal Wistar rats were cultured with 80% Dulbecoo's modified Eagle medium and 20% fetal bovine serum. An appropriate amount of xanthine and xanthine oxidase was added to the culture medium to increase the content of free radicals in cardiac cells. Variation in action potential and input impedance of cardiac myocytes indicated the oxidative damage to the membrane. The ultrastructure of heart cells, characteristically the myofilaments and mitochondria, was damaged. Electron spin resonance measurement demonstrated that xanthine and xanthine oxidase elevated the free radical content, while selenium (Se) and manganese (Mn) reduced the free radicals in cultured heart cells. Supplementation of 0.173 microgram/ml Se and 0.1 microgram/ml Mn into the culture medium separately or simultaneously antagonized the damage induced by xanthine and xanthine oxidase. The possible mechanism might be the production of superoxide anion free radical leading to free radical damage to cardiac cells. Se and Mn might play a role as scavengers through glutathione peroxidase and superoxide dismutase respectively and thus protect cardiac cells from free radical damage.

Effect of graded intravenous doses of urogastrone on duodenal bicarbonate secretion in conscious rats: evidence of a dose-response pattern.

In the present study, the effect of graded intravenous bolus injections of urogastrone, 0.5, 5, 25 and 50 micrograms/kg, on rat duodenal bicarbonate secretion was investigated. Perfused duodenal loops were prepared in rats in a strictly controlled fashion. After full recovery, different groups of rats were injected with intravenous graded bolus doses of urogastrone. During the following 45-min study period, duodenal pH and pCO2 were measured at 5-min intervals and bicarbonate secretion was calculated accordingly. Compared to controls, each dose of urogastrone caused a significant dose-response increase in duodenal bicarbonate secretion, measured either at each 5-min reading or as total 45-min output. These results provide the evidence that urogastrone may play a role in the humoral control of duodenal alkaline secretion.