OBJECTIVE: To investigate the protective effect of melatonin against myocardial ischemia reperfusion (IR) injury in isolated rat hearts and explore the underlying mechanisms. METHODS: The isolated hearts from 40 male SD rats were randomly divided into 4 groups (=10): the control group, where the hearts were perfused with KH solution for 175 min; IR group, where the hearts were subjected to global ischemia for 45 min followed by reperfusion for 120 min; IR+melatonin (Mel+IR) group, where melatonin (5 μmol/L) was administered to the hearts 1 min before ischemia and during the first 5 min of reperfusion, followed by 115 min of reperfusion; and IR+2, 3-butanedione monoxime (IR+BDM) group, where the hearts were treated with BDM (20 mmol/L) in the same manner as melatonin treatment. Myocardial injury in the isolated hearts was assessed based on myocardial injury area, caspase-3 activity, and expressions of cytochrome C and cleaved caspase-3 proteins. Cardiac contracture was assessed using HE staining and by detecting lactate dehydrogenase (LDH) activity and the content of cardiac troponin I (cTnI) in the coronary outflow, measurement of left ventricular end-diastolic pressure (LVEDP) and electron microscopy. The content of ATP in the cardiac tissue was also determined. RESULTS: Compared with those in the control group, the isolated hearts in IR group showed significantly larger myocardial injury area and higher caspase-3 activity and the protein expressions of cytochrome C and cleaved caspase-3 with significantly increased LDH activity and cTnI content in the coronary outflow and elevated LVEDP at the end of reperfusion; HE staining showed obvious fractures of the myocardial fibers and the content of ATP was significantly decreased in the cardiac tissue; electron microscopy revealed the development of contraction bands. In the isolated hearts with IR, treatment with Mel or BDM significantly reduced the myocardial injury area, caspase-3 activity, and protein expressions of cytochrome C and cleaved caspase-3, obviously inhibited LDH activity, lowered the content of cTnI and LVEDP, reduced myocardial fiber fracture, and increased ATP content in the cardiac tissue. Both Mel and BDM inhibited the formation of contraction bands in the isolated hearts with IR injury. CONCLUSIONS Mel can alleviate myocardial IR injury in isolated rat hearts by inhibiting cardiac contracture, the mechanism of which may involve the upregulation of ATP in the cardiac myocytes to lessen the tear of membrane and reduce cell content leakage.
Animals ; Heart ; drug effects ; Male ; Melatonin ; pharmacology ; therapeutic use ; Muscle Contraction ; drug effects ; Myocardial Reperfusion Injury ; drug therapy ; Myocytes, Cardiac ; drug effects ; Rats ; Rats, Sprague-Dawley

OBJECTIVE: To investigate the protective effect of melatonin against myocardial ischemia reperfusion (IR) injury in isolated rat hearts and explore the underlying mechanisms. METHODS: The isolated hearts from 40 male SD rats were randomly divided into 4 groups (=10): the control group, where the hearts were perfused with KH solution for 175 min; IR group, where the hearts were subjected to global ischemia for 45 min followed by reperfusion for 120 min; IR+melatonin (Mel+IR) group, where melatonin (5 μmol/L) was administered to the hearts 1 min before ischemia and during the first 5 min of reperfusion, followed by 115 min of reperfusion; and IR+2, 3-butanedione monoxime (IR+BDM) group, where the hearts were treated with BDM (20 mmol/L) in the same manner as melatonin treatment. Myocardial injury in the isolated hearts was assessed based on myocardial injury area, caspase-3 activity, and expressions of cytochrome C and cleaved caspase-3 proteins. Cardiac contracture was assessed using HE staining and by detecting lactate dehydrogenase (LDH) activity and the content of cardiac troponin I (cTnI) in the coronary outflow, measurement of left ventricular end-diastolic pressure (LVEDP) and electron microscopy. The content of ATP in the cardiac tissue was also determined. RESULTS: Compared with those in the control group, the isolated hearts in IR group showed significantly larger myocardial injury area and higher caspase-3 activity and the protein expressions of cytochrome C and cleaved caspase-3 with significantly increased LDH activity and cTnI content in the coronary outflow and elevated LVEDP at the end of reperfusion; HE staining showed obvious fractures of the myocardial fibers and the content of ATP was significantly decreased in the cardiac tissue; electron microscopy revealed the development of contraction bands. In the isolated hearts with IR, treatment with Mel or BDM significantly reduced the myocardial injury area, caspase-3 activity, and protein expressions of cytochrome C and cleaved caspase-3, obviously inhibited LDH activity, lowered the content of cTnI and LVEDP, reduced myocardial fiber fracture, and increased ATP content in the cardiac tissue. Both Mel and BDM inhibited the formation of contraction bands in the isolated hearts with IR injury. CONCLUSIONS Mel can alleviate myocardial IR injury in isolated rat hearts by inhibiting cardiac contracture, the mechanism of which may involve the upregulation of ATP in the cardiac myocytes to lessen the tear of membrane and reduce cell content leakage.
Animals ; Contracture ; Male ; Melatonin ; Myocardial Ischemia ; Myocardial Reperfusion Injury ; Myocardium ; Myocytes, Cardiac ; Rats ; Rats, Sprague-Dawley

Objective:To investigate the role of Na+/Ca2+ exchanger (NCX) in myocardial ischemiareperfusion injury and the underlying mechanisms.Methods:Forty Sprague-Dawley rats were divided into 4 groups randomly:a control group,a KBR7943 group,an ischemia-reperfusion group (IR group),and an IR plus KB-R7943 group (KB-R7943+IR group).Isolated Sprague Dawley male rat hearts underwent Langendorffperfusion.The ratio of left ventricular developed pressure (LVDP),left ventricular end-diastolic pressure (LVEDP),the infarct size of myocardium,and the lactate dehydrogenase (LDH) activity in the coronary flow was determined.HE staining was used to assess the change of myocardial morphology.Western blot was used to determine the levels of cleaved caspase-3,cytochrome c and the phosphorylation of Ca2+/calmodulin-dependent protein kinase Ⅱ (CaMKⅡ) and the Thr17 site ofphospholamban.Results:Compared with the control group,IR group significantly induced an enlarged infarct size,reduction of the ratio of LVDP,up-regulation of cytochrome c,cleaved caspase-3,p-CaMKⅡ and p-phospholamban,and increased in the activity of LDH,the level of LVEDP (P＜0.01) and the disordered myocardial morphology.These effects were significantly attenuated in the presence of KB-R7943 treatment (10 μmol/L).Conclusion:NCX mediates myocardial ischemia-reperfusion-induced cell apoptosis and necrosis through activation of CaMKⅡ.

Objective:To investigate the role of melatonin in calcium overload-induced heart injury.Methods:Thirty-two rats were divided into 4 groups:a control group (Control),a melatonin control group (Mel),a calcium overload group (CaP),and a calcium overload plus melatonin group (Mel+CaP).Isolated Sprague Dawley male rat hearts underwent Langendorffperfusion.Left ventricular developed pressure (LVDP) was calculated to evaluate the myocardial performance.Triphenyltetrazolium chloride staining was used to measure the infarct size of myocardium.Lactate dehydrogenase (LDH) activity in the coronary flow was determined.The expressions of caspase-3 and cytochrome c were determined by Western blot.The pathological morphological changes in myocardial fiber were analyzed by HE staining.Results:Compared with the control group,calcium overload significantly induced an enlarged infarct size (P＜0.01),accompanied by the disordered arrangement of myocardial fiber,up-regulation of cytochrome c and caspase-3 (P＜0.01),and the increased activity of LDH (P＜0.01).T hese effects were significantly attenuated by 10 μmol/L melatonin (P＜0.01).Conclusion:Melatonin can alleviate calcium overload-induced heart injury.

Objective To evaluate the inter -list equivalency of the disyllabic materials for Mandarin speech perception test (MSP) by measuring the speech recognition score of patients with cochlear implant (CI) .Methods According to Latin -square design ,disyllabic recognition scores (quiet background) were measured for each of the 10 phonemically balanced lists in 50 Mandarin-speaking CI users(aged 30 .44 ± 12 .71 years)in sound field .RM -ANOVA was administered to confirm the list equivalency .Results The sentence recognition scores were 59 .26% ± 23 .49% ,64 .31% ± 23 .35% ,59 .97% ± 23 .07% ,62 .40% ± 25 .16% ,62 .75% ± 24 .47% ,62 .29% ± 23 .55% , 62 .85% ± 24 .60% ,61 .35% ± 23 .73% ,61 .82% ± 25 .28% ,58 .83% ± 25 .13% ,respectively for the 10 lists .There was no significance difference in sentence recognition scores across the 10 disyllabic lists [F(9 ,490)=0 .255 ,P=0 .986>0 .05] .Conclusion The good inter -list equivalency of the disyllabic materials for Mandarin speech perception test (MSP) has been proved to be useful for assessing speech recognition performance of Mandarin -speaking CI users .

OBJECTIVETo investigate the changes in aorta morphology and Ca(2+)-activated K(+) (KCa) channel expression in the diabetic rats.

METHODSA diabetic rat model was established by a single intraperitoneal injection of streptozotocin (30 mg/kg) after a modified high fat and glucose diet for 8 weeks. Pathological changes in the aorta were observed with HE staining, elastic fiber staining, Masson's trichrome staining and immunohistochemistry. Both the mRNA and protein levels of KCa channels in the aorta were measured by RT-PCR and Western blotting.

RESULTSEarly atherosclerotic changes were observed in the aorta wall of the diabetic rats. The mRNA and protein levels of KCa1.1 channel α- and β-subunits were significantly decreased, while the expression of KCa3.1 channels was obviously enhanced in the middle layer of the aorta in the diabetic rats.

CONCLUSIONKCa channel switching in smooth muscles may play a role in the development of atherosclerosis in diabetic rats.

Animals ; Aorta ; pathology ; Atherosclerosis ; pathology ; Diabetes Mellitus, Experimental ; pathology ; Intermediate-Conductance Calcium-Activated Potassium Channels ; metabolism ; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits ; metabolism ; Male ; Muscle, Smooth, Vascular ; metabolism ; Rats ; Rats, Sprague-Dawley

Objective To study the distribution of brain dopamine transporter (DAT) in children with autism by single photon emission computed tomography (SPECT). Methods Brain SPECT imaging was performed in 10 autistic children and 10 normal children, and DAT distribution in different functional areas of brain were calculated and compared by semi-quantitative evaluation of tracer uptake. Results There were no differences in tracer uptake between left and right striatum either in autistic children or in normal children (P=0.556, 0.563), while the tracer uptake level in autistic children was significantly higher than that in normal children (P=0.018). Conclusions The striatum dopaminergic neurons are hyperactive in children with autism. SPECT is helpful for the diagnosis of autism.

Objective To investigate the changes in aorta morphology and Ca2+-activated K+ (KCa) channel expression in the diabetic rats. Methods A diabetic rat model was established by a single intraperitoneal injection of streptozotocin (30 mg/kg) after a modified high fat and glucose diet for 8 weeks. Pathological changes in the aorta were observed with HE staining, elastic fiber staining, Masson's trichrome staining and immunohistochemistry. Both the mRNA and protein levels of KCa channels in the aorta were measured by RT-PCR and Western blotting. Results Early atherosclerotic changes were observed in the aorta wall of the diabetic rats. The mRNA and protein levels of KCa1.1 channel α- and β-subunits were significantly decreased, while the expression of KCa3.1 channels was obviously enhanced in the middle layer of the aorta in the diabetic rats. Conclusion KCa channel switching in smooth muscles may play a role in the development of atherosclerosis in diabetic rats.

Objective To investigate the changes in aorta morphology and Ca2+-activated K+ (KCa) channel expression in the diabetic rats. Methods A diabetic rat model was established by a single intraperitoneal injection of streptozotocin (30 mg/kg) after a modified high fat and glucose diet for 8 weeks. Pathological changes in the aorta were observed with HE staining, elastic fiber staining, Masson's trichrome staining and immunohistochemistry. Both the mRNA and protein levels of KCa channels in the aorta were measured by RT-PCR and Western blotting. Results Early atherosclerotic changes were observed in the aorta wall of the diabetic rats. The mRNA and protein levels of KCa1.1 channel α- and β-subunits were significantly decreased, while the expression of KCa3.1 channels was obviously enhanced in the middle layer of the aorta in the diabetic rats. Conclusion KCa channel switching in smooth muscles may play a role in the development of atherosclerosis in diabetic rats.

OBJECTIVETo investigate the role of K(Ca)3.1 channel in the proliferation and migration of rat vascular smooth muscle cells of the proliferative phenotype.

METHODSRat vascular smooth muscle cells (VSMCs) were cultured with tissue adhesion method. The morphological characteristics of the fist and ninth passages of VSMCs were observed with light and electron microscopy and immunocytochemistry. The expressions of K(Ca)3.1 channel mRNA and protein in the cells were detected using RT-PCR and immunocytochemistry, respectively. MTT and transwell assay were employed to assess the effect of the K(Ca)3.1 channel blocker TRAM-34 on the proliferation and migration of VSMCs.

RESULTSThe first and ninth passages of VSMCs showed morphological characteristics of contractile and proliferative phenotypes, respectively. Compared with the first- passage cells, the ninth-passage VSMCs exhibited significantly increased K(Ca)3.1 channel mRNA and protein expressions with enhanced cell proliferation and migration (P<0.01), which was inhibited by the application of TRAM-34 (P<0.01). TRAM-34 produced no obvious effect on the first-passage VSMCs.

CONCLUSIONUpregulated expression of K(Ca)3.1 channel can promote the proliferation and migration of rat VSMCs of the proliferative phenotype.

Animals ; Cell Movement ; Cell Proliferation ; Cells, Cultured ; Large-Conductance Calcium-Activated Potassium Channels ; metabolism ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Myocytes, Smooth Muscle ; cytology ; metabolism ; Potassium Channel Blockers ; pharmacology ; Pyrazoles ; pharmacology ; Rats ; Rats, Sprague-Dawley