[ ABSTRACT] AIM: To study the protective effect of ischemia preconditioning ( IPC ) on ischemia/reperfusion ( IR)-damaged myocardium in young and old rats .METHODS: Male Wistar rats aged at 3 months ( young ) and 20 months ( old) were used to establish myocardial IPC model and IR model with the method of Langendorff heart perfusion . The rats were divided into young ischemia/reperfusion ( YIR) group, young ischemic preconditioning ( YPC) group, old ischemia/reperfusion ( OIR) group and old ischemic preconditioning ( OPC) group.Transmission electron microscopy was used to observe the ultrastructural changes of myocardial tissue and myocardial mitochondria .The myocardial infarction area was determined by TTC staining .The lactate dehydrogenase ( LDH) content in coronary effluent fluid and the levels of su-peroxide dismutase ( SOD) and malondialdehyde ( MDA) in myocardial tissues were detected by the method of colorimetry . The levels of nitrated and carbonylated proteins in myocardial tissue were measured by ELISA .The myocardial cell apopto-sis was analyzed by TUNEL assay .The mitochondrial respiratory function and mitochondrial permeability transition pore o-pening induced by calcium load were evaluated by oxygen electrode method .RESULTS: Compared with YIR group , the myocardial infarction area in YPC group was obviously smaller , SOD activity in myocardial tissues increased , LDH activity in coronary effluent fluid and the content of MDA decreased , and the levels of nitrated and carbonylated proteins in the car-diac tissues reduced .In YPC group, the mitochondrial membrane structure appeared intact , cristae of the mitochondria showed close arrangement , and the matrix was compressed under the electron microscope .Myocardial mitochondrial respir-atory control rate , state Ⅲoxygen consumption and the P/O ratio in YIR group all significantly increased , proton leak de-creased, mitochondrial swelling induced by calcium distinctly reduced , and myocardial apoptosis rate declined .No signifi-cant difference of the above indexes between OIR group and OPC group was observed .Compared with YPC group , myocar-dial ultrastructural damage increased clearly , cardiac oxidative stress increased , mitochondrial respiratory function de-clined, and cell apoptosis and necrosis increased in OPC group .CONCLUSION:Ischemic preconditioning has protective effect against myocardial IR injury in young rat hearts , while old rat hearts were less sensitive to ischemic preconditioning , leading to bluntness of cardioprotection with IPC in aging hearts .This may be related to mitochondrial injury and severe cel-lular apoptosis caused by increase of cardiac oxidative stress levels in the aging ischemic preconditioning heart .

ObjectiveTo investigate the regulatory effects of Xuanfu Daizhetang on a mouse model of allergic asthma induced by ovalbumin （OVA）. MethodSixty female BALB/c mice （6-8 weeks old， SPF） were randomly divided into groups. Ten mice were assigned to the normal group and given 0.2 mL of saline， while the remaining groups received intraperitoneal injections of Al（OH）₃ at 5 g·L^-1 and OVA at 1 g·L^-1. The mice were divided into normal group （10 mL·kg^-1 saline）， OVA model group （10 mL·kg^-1 saline）， dexamethasone group （OVA+DEX， 1 mg·kg^-1）， OVA+ low-dose Xuanfu Daizhetang group （OVA+XL， 7.065 g·kg^-1）， OVA+ medium-dose Xuanfu Daizhetang group （OVA+XM， 14.13 g·kg^-1）， and OVA+ high-dose Xuanfu Daizhetang group （OVA+XH， 28.26 g·kg^-1）. An OVA-induced asthma model was established in mice. Hematoxylin-eosin （HE） and periodic acid-Schiff （PAS） staining methods were used to observe bronchial tissue pathological changes. Enzyme-linked immunosorbent assay （ELISA） was performed to measure the levels of immunoglobulin E （IgE）， interleukin-4 （IL-4）， IL-5， IL-13， IL-17A， and γ interferon （IFN-γ） in bronchoalveolar lavage fluid. Western blot was used to detect the phosphorylation of extracellular signal-regulated kinase （ERK）， p38 mitogen-activated protein kinase （MAPK）， and c-Jun N-terminal kinase （JNK） proteins in lung tissue. ResultCompared with the normal group， the OVA model group showed increased inflammatory cell infiltration in mouse alveoli， elevated levels of IL-4， IL-5， IL-13， IL-17A， IFN-γ in bronchoalveolar lavage fluid， and IgE in serum （P<0.05， P<0.01）， and promoted phosphorylation of MAPK signaling pathway-related proteins. Compared with the model group， the OVA+XL， OVA+XM， and OVA+XH groups showed reduced inflammatory cell infiltration in mouse alveoli， decreased levels of IL-4， IL-5， IL-13， IL-17A， IFN-γ in bronchoalveolar lavage fluid， and IgE in serum （P<0.05， P<0.01）， and inhibited phosphorylation of MAPK signaling pathway-related proteins. ConclusionThe results of this study suggest that Xuanfu Daizhetang has potential anti-allergic asthma activity， providing a theoretical basis for its future clinical application.