Association of polymorphisms of potassium voltage-gated channel, KQT-like subfamily, member 1 and type 2 diabetes in Jiangsu province, China / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the association of polymorphisms in the potassium voltage-gated channel, KQT-like subfamily,member 1(KCNQ1) gene with type 2 diabetes in Chinese population from Jiangsu province.</p><p><b>METHODS</b>Subjects consisting of 2925 cases and 3281 controls were enrolled from a community based cohort study of type 2 diabetes in Wuxi in 2007 and a community based cross-sectional survey on chronic non-communicable disease in Nantong in 2009. Epidemiological questionnaire survey and physical examinations were conducted and 10 h overnight fasting blood samples of 5 ml were drawn for all subjects.Genotypes were determined by TaqMan OpenArray Genotyping System and i-PLEX Sequenom MassARRAY platform. The relationship between KCNQ1 gene polymorphism and risk of type 2 diabetes after adjustment for age,sex and body mass index (BMI) was analyzed.</p><p><b>RESULTS</b>The C allele of rs2237897, rs2237892 and rs2237895 at KCNQ1 increased the risk of type 2 diabetes with adjusted OR (95%CI) value being 1.41(1.30-1.54), 1.35(1.24-1.47), 1.22(1.12-1.33) respectively (all P value < 0.05) under the additive genetic model after adjusted by age,sex and BMI. Stratification analyses in additive genetic model showed that the C allele of rs2237897 increased the risk of type 2 diabetes in subgroups stratified by age ( ≤ 56 years and > 56 years), sex (females and males), BMI (< 24 kg/m(2) and ≥ 24 kg/m(2)) with OR (95%CI) value being 1.39(1.22-1.59), 1.43(1.28-1.60), 1.40(1.26-1.55), 1.44(1.26-1.66), 1.48(1.33-1.66), 1.34(1.17-1.53) respectively (all P value< 0.05).</p><p><b>CONCLUSION</b>Polymorphisms of rs2237897, rs2237892 and rs2237895 in the KCNQ1 gene were associated with occurrence of type 2 diabetes among Jiangsu province population.</p>

Single nucleotide polymorphism in flanking region of miR-30c influences the maturing process of miR-30c in lung carcinoma / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the effect of a common polymorphism rs928508(A/G) in flanking region of miR-30c on the expression of pri, pre and mature miR-30c, and discuss the effect of this polymorphism on the maturing process of miR-30c in lung carcinoma.</p><p><b>METHODS</b>The pGL3-promoter-miR-30c-A and pGL3-promoter-miR-30c-G luciferase plasmids were created containing A or G allele of miR-30c flanking region. Taqman assay was used to genotype rs928508 polymorphism in 50 lung cancer tissues. RT-PCR was performed to determine the expression of pri-miR-30c, pre-miR-30c, mature miR-30c and miR-30c host gene NFYC in the 50 lung cancer tissues.</p><p><b>RESULTS</b>The luciferase expression level of the pGL3-promoter-miR-30c-A construct group was not significantly different compared with that in the the pGL3-promoter-miR-30c-G construct group (A549 cells, P = 0.758; 293A cells, P = 0.554; CHO cells, P = 0.175). The results demonstrated that rs928508(A/G) variant had no effect on the transcriptional regulation of pri-miR-30c. In the genotype-phenotype collection analysis of the 50 lung cancer tissues, the expression of pre-miR-30c and mature miR-30c for rs928508 AG/GG genotypes showed significantly lower levels compared with those in the AA genotype (P = 0.009, P = 0.011). However, the expression of pri-miR-30c showed no significant difference between AG/GG genotypes and AA genotype. Similarly, the expression of host NFYC gene was correlated with pri-miR-30c, showed no significant difference between AG/GG genotypes and AA genotype.</p><p><b>CONCLUSION</b>The rs928508(A/G) polymorphism in flanking region of miR-30c could influence the processing from pri-miR-30c to mature miR-30c, but does not influence the transcription of pri-miR-30c.</p>

Random forest analysis of high dimensional case and control study of lung cancer / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the performance of random forest method as a SNP screening procedure in high dimensional case-control data of lung cancer.</p><p><b>METHODS</b>This study included 500 lung cancer patients and 517 controls. A total of 5 ml venous blood sample was collected from each participant. The genotypes were classified by GoldenGate platform, and 399 SNPs were selected. The random forest method was first applied to reduce the dimension, and then the traditional logistic regression method was used to analyze the variables and the genetic susceptibility between lung cancer and multiple SNPs was analyzed by AUC (areas under receiver operation characteristics (ROC) curves).</p><p><b>RESULTS</b>Fifty important variables, whose average importance scores were highest and whose error rates were lowest, were selected by random forest method. The importance scores of environmental variables (smoking, age and gender) were all listed at top 20, which were respectively 4.05, 3.12 and 1.16. After adjusting 3 environmental variables and false discovery rate (FDR), 6 SNPs were still significantly associated with lung cancer (FDR-P < 0.05). However, if traditional logistic regression analysis were directly applied, no significant SNPs were found. The likelihood testing result of AUC of the 2 ROC (one curve only included environmental variables and the other curve included environmental variables and SNPs) were 0.6491 ± 0.0172 and 0.6811 ± 0.0166 respectively; showed statistical significance of the association between the 6 SNPs and lung cancer (χ² = 43.82, P = 3.6×10⁻¹¹).</p><p><b>CONCLUSION</b>Random forest analysis could first remove the turbulent SNPs and then make the analysis by logistic regression method. This could improve the testing efficacy, which is significantly better than single logistic regression analysis.</p>

Cancer risk and key components of metabolic syndrome: a population-based prospective cohort study in Chinese / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The key components of metabolic syndrome (MS) are waist circumference, blood pressure, fast blood glucose, high density lipoprotein cholesterol (HDL-c) and triglycerides (TG). These components have, separately and jointly, been associated with an increased risk of cardiovascular diseases. In this study, we aimed to explore the association between MS components and cancer risk in a population-based cohort in China.</p><p><b>METHODS</b>We established a population-based cohort with 17 779 individuals aged 35 and above at baseline in 2004 and 2005 in Changzhou, Jiangsu Province, China. All participants were face-to-face interviewed to complete a questionnaire and were accepted physical examinations including blood tests for glucose and lipids and physical measurements for obesity and blood pressure. In 2009, a total of 16 284 subjects (6886 men and 9398 women, 91.6%) attended the flow-up interviews and the participants or their family members reported all the hospitalizations and diseases including cancer occurred during the follow-up period. Multivariate Cox regression was used to estimate the hazard ratios (HRs) of metabolic syndrome components and cancer incidence.</p><p><b>RESULTS</b>There was a dose-response association between cancer risk and the number of MS components presented at baseline (P for trend = 0.012) and the HR (95% confidence interval (CI)) was 2.63 (1.27 - 5.45) for subjects carrying 3 or more metabolic syndrome components after adjustment for possible confounding factors. Specifically, the multivariate-adjusted HRs (95%CIs) for cancer risk in subjects with central obesity, high fasting glucose, low HDL-c were 1.94 (1.01 - 3.74), 2.04 (1.10 - 3.77) and 2.05 (1.09 - 3.88), respectively.</p><p><b>CONCLUSIONS</b>In this population-based, prospective cohort study in China, we found MS components, e.g., central obesity, high fasting glucose, low HDL-c were risk factors for cancer development. Early intervention of MS components may be also beneficial to reduce cancer burden.</p>

Fatty acid desaturase 1 polymorphisms are associated with coronary heart disease in a Chinese population / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>A recent genome-wide association study in Caucasians revealed that three loci (rs174547 in fatty acid desaturase 1 (FADS1), rs2338104 near mevalonate kinase/methylmalonic aciduria, cobalamin deficiency, cblB type (MVK/MMAB) and rs10468017 near hepatic lipase (LIPC)) influence the plasma concentrations of high-density lipoprotein-cholesterol (HDL-C) and triglycerides (TG). However, there are few reports on the associations between these polymorphisms and plasma lipid concentrations in Chinese individuals. This study aimed to evaluate the associations between these three polymorphisms with HDL-C and TG concentrations, as well as coronary heart disease (CHD) susceptibility in Chinese individuals.</p><p><b>METHODS</b>We conducted a population-based case-control study in Chinese individuals to evaluate the associations between these three polymorphisms and HDL-C and TG concentrations, and also evaluated their associations with susceptibility to CHD. Genotypes were determined using polymerase chain reaction-restriction fragment length polymorphism assays and TaqMan genotyping assays.</p><p><b>RESULTS</b>We found significant differences in TG and HDL-C concentrations among the TT, TC and CC genotypes of FADS1 rs174547 (P=0.017 and 0.003, respectively, multiple linear regression). The CC variant of rs174547 was significantly associated with hyperlipidemia compared with the TT variant (adjusted odds ratio (OR)=1.71, 95% confidence intervals (CI): 1.16-2.54). The FADS1 rs174547 CC variant was also associated with significantly increased CHD risk compared with the TT and TC variant (adjusted OR=1.53, 95%CI: 1.01-2.31), and the effect was more evident among nonsmokers and females. The polymorphisms rs2338104 and rs10468017 did not significantly influence HDL-C or TG concentrations in this Chinese population.</p><p><b>CONCLUSION</b>rs174547 in FADS1 may contribute to the susceptibility of CHD by altering HDL-C and TG levels in Chinese individuals.</p>

Relationship between genetic polymorphism in microRNAs precursor and genetic predisposition of hepatocellular carcinoma / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between genetic polymorphism in microRNAs (miRNAs) precursor and genetic predisposition of hepatocellular carcinoma (HCC) in Chinese population.</p><p><b>METHODS</b>A case-control study including 963 HCC cases and 829 HBsAg positive controls and 852 HBsAg negative controls was conducted. hsa-mir-146a rs2910164 C→G and hsa-mir-196-a2 rs11614913 T→C were selected, where the genotypes were determined by the primer introduced restriction analysis-PCR (PIRA-PCR) assay. Odd ratios (ORs) and 95% confidence intervals (CIs) were evaluated by logistic regression analysis to investigate the relationship between onset risk of HCC and different genotypes.</p><p><b>RESULTS</b>The genotype frequencies of CC, CG and GG at rs2910164 gene locus were separately 34.5% (319/925), 48.6% (450/925) and 16.9% (156/925) in cases; 36.4% (274/753), 45.0% (339/753) and 18.6% (140/753) in HBsAg positive controls; and 36.1% (303/840), 46.0% (386/840) and 18.0% (151/840) in HBsAg negative controls. The genotype frequencies of TT, CT and CC at rs11614913 were respectively 29.7% (277/934), 48.1% (449/934) and 22.3% (208/934) in cases; 30.3% (238/785), 51.0% (400/785) and 18.7% (147/785) in HBsAg positive controls; and 28.6% (239/837), 49.8% (417/837) and 21.6% (181/837) in HBsAg negative controls. No significant relationships were observed between these two single nucleotide polymorphisms (SNPs) and onset risk of HCC after adjusting the factors as age, gender, smoking and drinking status in comparison with HBsAg positive controls: hsa-mir-146a rs2910164 (CG + GG vs CC): adjusting OR = 1.10, 95%CI: 0.90 - 1.36; hsa-mir-196-a2 rs11614913 (CC + CT vs TT): adjusting OR = 1.01, 95%CI: 0.81 - 1.25; as well as in comparison with HBsAg negative controls: hsa-mir-146a rs2910164 (CG + GG vs CC): adjusting OR = 1.06, 95%CI: 0.87 - 1.29; hsa-mir-196-a2 rs11614913 (CC + CT vs TT): adjusting OR = 0.94, 95%CI: 0.76 - 1.16. As well, no significant relationships were observed between these two SNPs and onset risk of HCC in the subgroups stratified by age, gender, smoking and drinking status.</p><p><b>CONCLUSION</b>hsa-mir-146a rs2910164 C→G and hsa-mir-196-a2 rs11614913 T→C may not play an important role in the HCC predisposition among Chinese populations.</p>

The relationship between gene polymorphism of telomerase reverse transcriptase and susceptibility to hepatocellular carcinoma / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the correlation between single-nucleotide polymorphisms (SNPs) of telomerase reverse transcriptase (TERT) rs2736098 and rs2736100 and the susceptibility to hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>This case-control study design included 1300 diagnosed HCC patients with HBsAg positive and 1344 HBsAg positive people as control-group.rs2736098 and rs2736100 on TERT were selected as research sites, whose polymorphisms were detected by TaqMan allelic discrimination assay. The OR values (95%CI) were calculated by logistic regression to compare the correlation between different genotype and susceptibility to HCC.</p><p><b>RESULTS</b>The distribution frequencies of three genotypes as GG, AG and AA on rs2736098 were separately 39.3% (500/1273), 44.2% (563/1273) and 16.5% (210/1273) in case group; while respectively 39.6% (526/1328), 45.5% (604/1328) and 14.9% (198/1328) in control group. The distribution frequencies of three genotypes as AA, AC and CC on rs2736100 were separately 33.7% (428/1269), 49.9% (633/1269) and 16.4% (208/1269) in case group; while respectively 34.0% (449/1322), 49.2% (651/1322) and 16.8% (222/1322) in control group. The multi-variates logistic regression analysis showed that there was no significant difference between rs2736098 mutated A carriers and genotype GG carriers in the susceptibility to HCC after adjusting by age, sex, smoking and drinking factors (rs2736098, AA + AG vs GG: adjusted OR = 1.00 (95%CI: 0.86 - 1.18)); and there was no significant different between rs2736100 mutated C carriers and genotype AA carriers in the susceptibility to HCC either (AC + CC vs AA: adjusted OR = 1.03 (95%CI: 0.87 - 1.22)).</p><p><b>CONCLUSION</b>The polymorphisms of rs2736098 and rs2736100 on TERT may not play a landmark role in susceptibility to HCC among Chinese population.</p>

Relationship between genetic polymorphism of promoter region let-7 and genetic susceptibility to hepatocellular carcinoma / 中华预防医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to discuss the relationship between genetic polymorphism of promoter region let-7 and genetic susceptibility to hepatocellular carcinoma (HCC) in Chinese population.</p><p><b>METHODS</b>In this case-control study, 1300 cases of HBV positive patients were recruited in case group and another 1344 cases of persistent chronic HBV carriers were selected as control. 5 ml of blood sample was collected from each subject, from which the DNA was extracted; and rs10877887 and rs13293512 in promoter region let-7 were selected as the study sites. The polymorphism was detected by TaqMan allelic discrimination assay and the OR value (95%CI) was evaluated by Logistic Regression Method to analyze the relationship between susceptibility to HCC and different genotypes.</p><p><b>RESULTS</b>The frequencies of genotype TT, CT and CC in site rs10877887 were 43.0% (542/1261), 44.7% (564/1261) and 12.3% (155/1261) respectively in case group; while separately 44.0% (581/1319), 44.4% (585/1319) and 11.6% (153/1319)in control group. The frequencies of genotype TT, CT and CC in site rs13293512 were 32.0% (406/1270), 48.1% (611/1270) and 19.9% (253/1270) respectively in case group; while separately 33.1% (427/1291), 49.4% (638/1291) and 17.5% (226/1291) in control group. The results of multifactor logistic regression analysis showed no statistical significance in the relationship between different genotype TT, mutated genotype C in site rs10877887 and susceptibility to HCC (CC + CT vs TT, adjusted OR = 1.05, 95%CI: 0.90 - 1.23); and either no statistical significance in the relationship between different genotype TT, mutated genotype C in site rs13293512 and susceptibility to HCC (CC + CT vs TT, adjusted OR = 1.06, 95%CI: 0.89 - 1.25). The united-analysis of the two sites showed the frequencies of 0, 1, 2 and 3-4 mutated-genotype C were 13.3% (164/1235), 36.2% (447/1235), 33.0% (408/1235) and 17.5% (216/1235) respectively in case group; and separately 14.2% (181/1269), 37.0% (469/1269), 33.1% (420/1269) and 15.7% (199/1269) in control group. The susceptibility to HCC in 1,2,3-4 mutated-genotype C carriers were 1.05 (0.81 - 1.34), 1.07 (0.83 - 1.38) and 1.22 (0.91 - 1.62) times of the non-mutated genotype subjects; but there was no statistical significance (Wald χ(2) = 1.79, P = 0.181).</p><p><b>CONCLUSION</b>The polymorphism of study sites rs10877887 and rs13293512 may not be the biomarker of susceptibility to HCC in Chinese.</p>

The association of polymorphisms of CDT1 and GMNN gene with the risk of breast cancer in Chinese women: a case-control analysis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the association of polymorphisms of CDT1 and GMNN gene, two important genes participating in DNA replication, with the risk of sporadic breast cancer.</p><p><b>METHODS</b>Using polymerase chain reaction-restriction fragment length polymorphism (PCR - RFLP) and the primer-introduced restriction analysis (PIRA)-PCR assay to genotype the CDT1 838G/A and GMNN 387C/A polymorphisms in a case-control study of 427 breast cancer cases and 477 cancer-free controls in a Chinese population.</p><p><b>RESULTS</b>No significant association of the CDT1 838G/A and GMNN 387C/A polymorphisms with the risk of breast cancer was found (adjusted OR:1.16, 95% CI:0.88-1.54 for CDT1 GA+AA genotypes and adjusted OR:0.90, 95% CI:0.67-1.21 for GMNN CA+AA genotypes). However, in the stratified analyses, a significant association of CDT1 GA+AA genotypes with breast cancer risk among subjects with family history of cancer was found (adjusted OR:2.21, 95% CI:1.20-4.09).</p><p><b>CONCLUSION</b>These findings suggest that the CDT1 838G/A and GMNN 387C/A polymorphisms may not play a major role in the etiology of breast cancer, but CDT1 variant may have a potential role only in genetically susceptible women.</p>

Association of two genetic polymorphisms in the 5'untranslated region of exon 2 of the p73 gene and risk of lung cancer / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the relationship between two potential functional polymorphisms in exon 2 of the p73 gene and the susceptibility of lung cancer.</p><p><b>METHODS</b>Genotypes were determined by polymerase chain reaction-single stand conformation polymorphism (PCR-SSCP) method in 425 histologically-confirmed lung cancer cases and 588 cancer-free controls, frequency-matched by age and sex.</p><p><b>RESULTS</b>The two polymorphisms were in complete linkage disequilibrium and the frequencies of variant p73 AT haplotype (A4T14) were less commonly seen in the cases (0.225) than in the controls (0.287) (P = 0.0018). Compared with the p73 GC/GC homozygotes, both the AT/AT variant homozygotes and GC/AT heterozygotes were associated with a significantly decreased risk [adjusted odds ratio (OR) = 0.45, 95% confidence interval (CI) = 0.26 - 0.80 and OR = 0.70, 95% CI = 0.53-0.92, respectively].</p><p><b>CONCLUSION</b>These results suggested that this p73 dinucleotide polymorphism might have had a role to play in the susceptibility of lung cancer.</p>

Study on the association of ABCA1 gene common variants with the risk of coronary atherosclerotic heart disease / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the association of R219K and M883I polymorphisms of ATP binding cassette transporter 1 gene with lipid metabolism and the susceptibility to coronary atherosclerotic heart disease in Chinese population.</p><p><b>METHODS</b>Genotypes were determined by PCR-restriction fragment length polymorphism and Primer introduced restriction analysis-PCR techniques, respectively, in 248 unrelated CHD-free controls and 224 CHD cases.</p><p><b>RESULTS</b>Smoking, high blood pressure and high serum glucose were independent risk factors for CHD. Multivariate logistic regression analysis revealed that individuals carrying at least one 219K variant allele (RK + KK genotypes) had a significantly decreased risk for CHD (adjusted OR = 0.41; 95% CI = 0.27-0.61) compared with the wild-type genotype (219RR) and only 883II homozygotes displayed a decreased risk for CHD (adjusted OR = 0.54; 95% CI = 0.26-1.11) compared with 883MM and 883MI genotypes. Furthermore, compared with individuals with both wild genotypes (219 RR and 883 MM or 883 MI) other individuals with all other assembly genotypes had a significantly decreased risk (adjusted OR = 0.39, 95% CI = 0.26-0.60). Plasma HDL-C in 219K allele carriers were markedly higher than those in 219 K non-carriers in controls (P = 0.037).</p><p><b>CONCLUSION</b>The ABCA1 R219K polymorphism may be involved in the variability of serum HDL-C and the susceptibility to coronary artery disease.</p>

Protective effect of mitochondrial ATP-sensitive potassium channel opener on rat heart during hypothermic preservation / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate whether the mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) opener diazoxide as an additive to cardioplegia solution could enhance myocardial protection during hypothermic preservation of the rat heart.</p><p><b>METHODS</b>The Langendorff model of isolated rat heart was used. After equilibrium, the hearts were stored in Celsior cardioplegia solution at 4 degree with or without supplement of diazoxide for 3 or 8 h followed by 60 minutes reperfusion. The recovery of cardiac contractile function, myocardial enzyme leakage in the coronary effluent, and myocardial water content were determined. The myocardial ultrastructure was also observed.</p><p><b>RESULT</b>(1) Treatment of diazoxide improved the recovery of left ventricular developed pressure and decreased the leakage of myocardial enzymes, lactate dehydrogenase (LDH) and creatine kinase (CK), at the 2nd and 4th minute of reperfusion of rat heart after hypothermic preservation for 3 h. (2) After hypothermic preservation for 8 h, diazoxide improved the recovery of left ventricular developed pressure and decreased the leakage of myocardial enzymes (LDH, CK and glutamic oxalic transaminase) during reperfusion. Moreover, left ventricular end-diastolic pressure was significantly lower in diazoxide-treated hearts than that of hearts in Celsior solution. (3) Diazoxide significantly decreased the water content of myocardium and increased coronary flow of the hearts compared with those in control after hypothermic preservation for 8 h. (4) Impairment of myocardial ultrastructure after 8 h hypothermic preservation was alleviated in hearts treated with 30 mol/L diazoxide. (5) The cardiac effects of 30 mol/L diazoxide were attenuated by a mitoK(ATP) blocker 5-hydroxydecanoate (100 micromol/L).</p><p><b>CONCLUSION</b>Diazoxide as a supplementation in cardioplegia solution could enhance myocardial protection during hypothermic heart preservation via opening of mitochondrial K(ATP) channel.</p>

Association of two exonic genetic polymorphisms in the DNA repair gene XPC with risk of lung cancer in Chinese population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the relationship between two exonic polymorphisms of DNA repair gene XPC and the susceptibility to lung cancer.</p><p><b>METHODS</b>Genotypes were determined by the primer introduced restriction analysis-PCR(PIRA-PCR) and the PCR-restriction fragment length polymorphism(PCR-RFLP) approaches, respectively, in 320 histologically-confirmed lung cancer cases and 322 age and sex frequency-matched cancer-free controls.</p><p><b>RESULTS</b>Multivariate logistic regression analysis revealed that individuals carrying at least one 499Val variant allele (Ala/Val + Val/Val genotypes) had a significantly increased risk for lung cancer (adjusted OR=1.54; 95%CI: 1.11-2.14), compared with the wild-type genotype (499Ala/Ala). Furthermore, individuals with both putative risk genotypes had a significantly higher risk (adjusted OR=2.55; 95%CI: 1.45-4.52), compared with those with both wild-genotypes. In addition, a potential super multiplicative gene-environment interaction between Ala499Val genotypes and smoking on lung cancer risk was unveiled. The odds ratios of lung cancer for individuals with both putative risk genotypes were 2.63 (95%CI=1.23-5.62) in nonsmokers and 7.36 (95%CI=3.19-17.0) in smokers, respectively.</p><p><b>CONCLUSION</b>These findings support the hypothesis that these two XPC variants may contribute to the risk of developing lung cancer.</p>

The protective effect of diazoxide on long-term heart preservation / 生理学报

Prolongation of the duration of heart preservation in vitro is very important in clinical heart transplantation. Previous studies have shown that mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) plays an important role in cardioprotective effect. The purpose of this study was to assess whether the mitoK(ATP) opener diazoxide as an additive to cardioplegia solution could enhance myocardial protection during long-term hypothermic preservation of the rat heart. Langendorff model of isolated rat heart was used. After 30 min stabilization of perfusion, the hearts were stored in Celsior cardioplegia solution at 4 degrees C with (15, 30 and 45 micromol/L) or without diazoxide, a mitoK(ATP) channel opener, for 10 h followed by 60 min reperfusion. The recovery of cardiac contractile function, myocardial enzyme leakage in the coronary effluent, and myocardial water content were determined. The myocardial ultrastructure was also observed. We found that: (1) Diazoxide treatment improved the recovery of left ventricular developed pressure and +/-dp/dt(max) dose-dependently. Left ventricular end-diastolic pressure was significantly lower in diazoxide-treated hearts than that of hearts in Celsior solution after hypothermic preservation for 10 h. (2) Diazoxide at 30 and 45 micromol/L significantly decreased the water content of myocardium and increased coronary flow of the hearts compared to those in control. (3) The leakage of myocardial enzymes (lactate dehydrogenase, creatine kinase and glutamate-oxaloacetate transaminase) in the coronary effluent was significantly reduced in diazoxide-treated hearts. (4) Impairment of myocardial ultrastructure after 10 h hypothermic preservation was alleviated in hearts treated with 30 micromol/L diazoxide. (5) The cardiac effects of 30 micromol/L diazoxide were attenuated by a mitoK(ATP) blocker 5-hydroxydecanoate (5-HD, 100 micromol/L). These results indicate that diazoxide as a supplementation in cardioplegia solution could enhance myocardial protection during long-term hypothermic heart preservation via opening of mitochondrial K(ATP) channel.