AIM: To study the origin of calcium necessary for agonist-induced contraction of the distal colon in rats.METHODS: The change in intracellular calcium concentration ([Ca2+]i) evoked by elevating external Ca2+ was dete...AIM: To study the origin of calcium necessary for agonist-induced contraction of the distal colon in rats.METHODS: The change in intracellular calcium concentration ([Ca2+]i) evoked by elevating external Ca2+ was detected by fura 2/AM fluorescence. Contractile activity was measured with a force displacement transducer. Tension was continuously monitored and recorded using a Powerlab 4/25T data acquisition system with an ML110 bridge bioelectric physiographic amplifier.RESULTS: Store depletion induced Ca2+ influx had an effect on [Ca2+]i. In nominally Ca2+-free medium, the sarco-endoplasmic reticulum Ca2+-ATPase inhibitor thapsigargin (1 μmol/L) increased [Ca2+]i from 68 to 241 nmol/L, and to 458 (P < 0.01) and 1006 nmol/L (P < 0.01), respectively, when 1.5 mmol/L and 3.0 mmol/L extracellular Ca2+ was reintroduced. Furthermore, the change in [Ca2+]i was observed with verapamil (5 μmol/L), La3+ (1 mmol/L) or KCl (40 mmol/L) in the bathing solution. These channels were sensitive to La3+ (P < 0.01), insensitive to verapamil, and voltage independent. In isolated distal colons we found that in normal Krebs solution, contraction induced by acetylcholine (ACh) was partially inhibited by verapamil, and the inhibitory rate was 41% (P < 0.05). On the other hand, in Ca2+-free Krebs solution, ACh induced transient contraction due to Ca2+ release from the intracellular stores. The transient contraction lasted until the Ca2+ store was depleted. Restoration of extracellular Ca2+ in the presence of atropine produced contraction, mainly due to Ca2+ influx. Such contraction was not inhibited by verapamil, but was decreased by La3+ (50 μmol/L) from 0.96 to 0.72 g (P < 0.01). CONCLUSION: The predominant source of activator Ca2+ for the contractile response to agonist is extracellular Ca2+, and intracellular Ca2+ has little role to play in mediating excitation-contraction coupling by agonists in rat distal colon smooth muscle in vitro. The influx of extracellular Ca2+ is mainly mediated through voltage-, receptor- and store-operated Ca2+ channels, which can be used as an alternative to develop new drugs targeted on the dysfunction of digestive tract motility.展开更多
The coexistence of hydrogen-containing materials and radioactive substances in source rocks is universal.Few documents have researched whether the latter can radiate the former to generate hydrogen gas(H2)as well as t...The coexistence of hydrogen-containing materials and radioactive substances in source rocks is universal.Few documents have researched whether the latter can radiate the former to generate hydrogen gas(H2)as well as the factors controlling this process.This work conducted a series of radiation experiments to address this issue.Samples were placed in sealed Pyrex glass containers and subject to cobalt(60 Co)γirradiation and components and contents of resultant gases were analyzed using gas-chromatography.The results show that all the samples released variable amounts of H2 after irradiation and that the yield(H2)of decane is lower than that of 3-tetradecylthiophene but higher than that of distilled water,which implies that a weaker H-X bond energy(X indicates O,C or other element)in homogeneous materials corresponds with increased yield(H2).The yields(H2)of samples decreased with the decreasing solutions concentrations in sequence from mixed salts solution,KCl solution,Yellow Sea water,oil field water,gypsum solution to distilled water.The experimental results also show that the yield(H2)of distilled water with montmorillonite is higher than that of distilled water with kaolinite,because due to the larger specific surface area,ion exchange capacity and more effective energy transfer effect of montmorillonite.Meanwhile,the irradiation of oxygen-and carbon-containing materials also releases O2 and CH4.The production of H2 via the irradiation of hydrogen-containing materials makes the involvement of exogenous H2 into hydrocarbon generation possible,which can enhance the hydrocarbon volume and optimize crude oil.展开更多
基金Supported by Grants from the fund of Wannan Medical College Scientific Research, No. WK 200729
文摘AIM: To study the origin of calcium necessary for agonist-induced contraction of the distal colon in rats.METHODS: The change in intracellular calcium concentration ([Ca2+]i) evoked by elevating external Ca2+ was detected by fura 2/AM fluorescence. Contractile activity was measured with a force displacement transducer. Tension was continuously monitored and recorded using a Powerlab 4/25T data acquisition system with an ML110 bridge bioelectric physiographic amplifier.RESULTS: Store depletion induced Ca2+ influx had an effect on [Ca2+]i. In nominally Ca2+-free medium, the sarco-endoplasmic reticulum Ca2+-ATPase inhibitor thapsigargin (1 μmol/L) increased [Ca2+]i from 68 to 241 nmol/L, and to 458 (P < 0.01) and 1006 nmol/L (P < 0.01), respectively, when 1.5 mmol/L and 3.0 mmol/L extracellular Ca2+ was reintroduced. Furthermore, the change in [Ca2+]i was observed with verapamil (5 μmol/L), La3+ (1 mmol/L) or KCl (40 mmol/L) in the bathing solution. These channels were sensitive to La3+ (P < 0.01), insensitive to verapamil, and voltage independent. In isolated distal colons we found that in normal Krebs solution, contraction induced by acetylcholine (ACh) was partially inhibited by verapamil, and the inhibitory rate was 41% (P < 0.05). On the other hand, in Ca2+-free Krebs solution, ACh induced transient contraction due to Ca2+ release from the intracellular stores. The transient contraction lasted until the Ca2+ store was depleted. Restoration of extracellular Ca2+ in the presence of atropine produced contraction, mainly due to Ca2+ influx. Such contraction was not inhibited by verapamil, but was decreased by La3+ (50 μmol/L) from 0.96 to 0.72 g (P < 0.01). CONCLUSION: The predominant source of activator Ca2+ for the contractile response to agonist is extracellular Ca2+, and intracellular Ca2+ has little role to play in mediating excitation-contraction coupling by agonists in rat distal colon smooth muscle in vitro. The influx of extracellular Ca2+ is mainly mediated through voltage-, receptor- and store-operated Ca2+ channels, which can be used as an alternative to develop new drugs targeted on the dysfunction of digestive tract motility.
基金financially supported by the National Natural Science Foundation of China(grants No.41330315 and 41402093)the Education Fund Project of Shaanxi Province(grants No.14JK1732)
文摘The coexistence of hydrogen-containing materials and radioactive substances in source rocks is universal.Few documents have researched whether the latter can radiate the former to generate hydrogen gas(H2)as well as the factors controlling this process.This work conducted a series of radiation experiments to address this issue.Samples were placed in sealed Pyrex glass containers and subject to cobalt(60 Co)γirradiation and components and contents of resultant gases were analyzed using gas-chromatography.The results show that all the samples released variable amounts of H2 after irradiation and that the yield(H2)of decane is lower than that of 3-tetradecylthiophene but higher than that of distilled water,which implies that a weaker H-X bond energy(X indicates O,C or other element)in homogeneous materials corresponds with increased yield(H2).The yields(H2)of samples decreased with the decreasing solutions concentrations in sequence from mixed salts solution,KCl solution,Yellow Sea water,oil field water,gypsum solution to distilled water.The experimental results also show that the yield(H2)of distilled water with montmorillonite is higher than that of distilled water with kaolinite,because due to the larger specific surface area,ion exchange capacity and more effective energy transfer effect of montmorillonite.Meanwhile,the irradiation of oxygen-and carbon-containing materials also releases O2 and CH4.The production of H2 via the irradiation of hydrogen-containing materials makes the involvement of exogenous H2 into hydrocarbon generation possible,which can enhance the hydrocarbon volume and optimize crude oil.
