| In modern society, Inferior meat quality has been a great increasing problem which people pay more attention. As already known heat temperature is capable of causing lower pH,pale meat and a reduction in water-holding capacity, and so on. Whereas high temperature impact the quality of poultry meat via increasing Ca2+ concentration is not clear. Therefore, In this study, we will sought to determine the mechanism in vivo and in vitro initially.1,Effect of high temperature on rectal temperature, respiration rate and MDA, SOD,GSH-PX of broilers pectoral muscleThree hundreds male broilers were divided into four groups with eight replicates, fifteen broilers per replicate. Group one was control group, kept in 25℃, group two was pari-feeding group with the temperature of 25℃, group three was a high-temperature group, and group was high temperature +vitamin E. Broilers were killed at the seventh day and the fourteenth day.The ambient high temperature leaded to increase the rectal temperature and respiration rate significantly(P<0.05); this also increased the activity of MDA, SOD and GSH-PX(P<0.05). Furthermore, addition of vitamin E(150mg/kg) tend to decrease the rectal temperature, and respiration rate, but kept non-significantly.2,Effect of high temperature on lactate content and the meat quality of broilers pectoral muscleIn environment control chambers, broilers were kept for 7days and 14days. The experiment proved that at both the 7th day and 14th day high temperature lead to an increasing of lactate content(P<0.05), then pHi and pHu decreased(P<0.05). And L*,drip loss and shear force increased in pectoral muscle was found. Addition vitamin E in diet, tend to decrease the lactate content, but non-significantly(P<0.05). Whereas decreased the drip loss, shear force,significantly, caused an increase of pHi and pHu(P<0.05) .3,Impact of the ambient high temperature on cytosolic Ca2+concentration and lactate levels in satellite cells in the pectoral muscle of broilersPrimary satellite cells were cultured in 96-well plates. Experiment consisted of 2 treatment groups: a high-temperature group (treated at 40℃,then to 44℃30 minutes later) and a control group (at 25℃). Eight wells were used for each group and 100μL (1×106cells/mL) of suspended satellite cells was added to each well. Then the Ca2+concentration was recorded fluorescence microplate reader.At 25℃and 40℃the cytosolic calcium concentration remained almost stable, and kept non-significantly(P>0.05). At 44℃however, the cytosolic calcium concentration increased significantly with the 30 minutes(P<0.05).six groups of primary satellite cells from the breast tissue of broilers were treated separately at a high temperature(44℃) for 10, 20, 30, 40, 50 and 60min. The cytosolic lactate content was then determined using commercial colorimetric diagnostic kits from the Jiancheng Biochemical Institute. The cytosolic lactate in primary satellite cell of breast tissue from broilers tended to increase over the period of 1 hr. When the suspended cells were cultured from 40 to 50min at 44℃, the cytosolic lactate content increased significantly(P<0.05).The experiment proved that the cyclic high temperature increase the cytosolic calcium concentration and lactate content.4,Impact of cytosolic calcium concentration to lactate productionThe experimental samples were allocated to 5 treatment groups: Group 1 was a control group containing only suspended satellite cells, Group 2 contained suspended satellite cells and 2mM DMSO, and Group 3 contained suspended satellite cells and 2mM calcium ionophore(A23187), these three groups were all incubated at 40℃for an hour. Group 4 was a high-temperature group contained the same concentration of suspended cells, and Group5 with the addition of 1mM intracellular Ca2+ chelating agent(BAPTA-AM). These two groups were cultured at 44℃for 1 hr.Under these conditions, the intracellular Ca2+ concentration in Group 2 and 3 increased and was coupled with a non-significantly increase in lactate content (P>0.05). Group 4 was cultured in 44℃, and the lactate content was significantly(P<0.05) higher then that of Group 1 which was cultured at 40℃. In group 5 injected which was treated with BAPTA-AM, the intracellular Ca2+ concentration decreased and the lactate content decreased significantly(P<0.05). The experiment proved that altering the intracellular Ca2+ concentration impacts on the cytosolic lactate content. High temperature impact on cytosolic lactate content of sallitate cells by changing the intracellular Ca2+ concentration.5,Impact of high temperature on the activity of RyR and InsP3 receptor in satellite cellsThe experimental samples were allocated to 3 treatment groups: Group 1 was a control group containing only suspended satellite cells, Group 2 contained suspended satellite cells and 50μmol/L ruthenium red, and Group 3 contained suspended satellite cells and 50μmol/L 2-Aminoethoxydiphenyl borate (2-APB). Three groups were all cultured at 44℃for an hour.The cytosolic Ca2+ concentration in group 1 , group 2 and group 3 tend to increased, but group 2 kept significantly lower then group 1 (P<0.05). Group 3 and group 1 has non-significantly difference(P>0.05). The experiment proved that the ambient high temperature activated the RyR calcium channel, and released calcium to cytosolic, then increased the intracellular Ca2+ concentration; whereas the InsP3 calcium channel has non-siginificant effect in the process.In summary, the present finding that high temperature conditions increase the intracellular Ca2+ concentration and lactate formation via activity the RyR receptor on sarcoplasmic reticulum of the satellite cells. And then, lead to a lower pH,paler meat,higher drip loss and final in inferior meat quality.
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