[Clinical characteristics of patients with indication of cardiac implantable electronic devices implantation complicating with acute pulmonary thromboembolism].

Objective: To investigate the clinical characteristics of inpatients with the indication of cardiac implantable electronic devices (CIED) therapy and combined acute pulmonary thromboembolism (APTE). Methods: We retrospectively screened 8 641 inpatients who admitted with the indication of CIED implantation in Fuwai Hospital from January 2014 to May 2019. The clinical characteristics, management strategies and clinical outcome were analyzed for patients diagnosed as APTE. Results: APTE were identified in 45 (5‰) patients in this cohort, there were 18(40%) male patients, the average age was (73±8) years old and body mass index was (27±10) kg/m2.Thirty-two (70%) patients were at intermediate-risk and 13 (30%) at low-risk. Anti-coagulation therapy was initiated in 38(84%) patients, and 30 patients underwent CIED implantation (27 pacemaker, 2 CRT and 1 ICD). No postoperative bleeding or pocket hematoma were detected in the 23 patients taking anticoagulation medication before implantation. During an average of (30±7) months' follow up, thrombus was dissolved in 20 patients, hemorrhage complications were observed in 2 patients (1 cerebral hemorrhage and 1 hematuria), anticoagulation therapy was discontinued in these 2 patients. Among 15 patients without immediate CIED implantation and treated with anticoagulation therapy during hospitalization, 2 patients developed complete paroxysmal Ⅲ° atrioventricular block, and recovered after therapy during hospitalization. Seven patients were re-hospitalized for CIED implantation due to bradycardia. Five patients died during follow-up (3 sudden cardiac death, 1 APTE combined with cerebral infarction, and 1 pulmonary infection). Conclusion: APTE is not rare in patients with the indication of CIED implantation, CIED implantation and anti-coagulation therapy are safe for these patients, and transient atrioventricular block could be detected in APTE patients.

[Effects of NOX4 on radiosensitivity of nasopharyngeal carcinoma cells by activating the PI3K/AKT pathway].

Objective: To explore the relationship between NOX4 and radiosensitivity of nasopharyngeal carcinoma cells. Methods: Western blot was used to test the expression of NOX4 in nasopharyngeal carcinoma cells (CNE1, CNE2 and HONE1) and normal nasopharyngeal epithelial cells (NP69). The lentiviral vectors for RNA interference and overexpression of NOX4 gene were constructed and nasopharyngeal carcinoma cells were transfected. After treatment with radiation or/and PI3K/AKT inhibitor LY294002, the expressions of related proteins in cells were tested by Western blot, and the cell proliferation was detected by CCK-8 assay and the cell apoptosis was determined by flow cytometry. GraphPad Prism 5 was used for statistical analysis, and P<0.05 was statistically significant. Results: The expressions of NOX4 in nasopharyngeal carcinoma cells were higher than those in normal nasopharyngeal epithelial cells. Compared with the siNC group, the siNOX4 group of nasopharyngeal carcinoma cell had lower proliferation capacity [72 h absorbance (A) value:1.16 vs. 0.75] and higher apoptosis rate (2.9% vs. 10.0%). In contrast,compared with the vector group, the NOX4 group of nasopharyngeal carcinoma cell had higher proliferation capacity [72 h absorbance (A) value: 1.01 vs. 1.32] and lower apoptotic rate (1.7% vs. 1.1%).Treatment with LY294002 for nasopharyngeal carcinoma cells of NOX4 overexpression,compared with the NOX4 group, the proliferation ability of nasopharyngeal carcinoma cells in the NOX4+LY294002 group was reduced (72 h absorbance (A) value: 1.32 vs. 0.77), while the apoptotic rate was increased (1.1% vs. 3.1%).Treatment with radiotherapy, compared with the siNC/Vector group, the proliferation ability of nasopharyngeal carcinoma cells in the siNOX4 group was reduced (72 h absorbance (A) value: 0.72 vs. 0.33), and the apoptotic rate was increased (7.8% vs. 17.3%). However, in the NOX4 group, the proliferation of nasopharyngeal carcinoma cells was enhanced (72 h absorbance (A) value:0.65 vs. 0.78), and the apoptotic rate was reduced (8.1% vs. 3.8%). Compared with the NOX4+radiation group, the proliferation ability of nasopharyngeal carcinoma cells in the NOX4+radiation+LY294002 group was reduced (72 h absorbance (A) value: 0.79 vs. 0.56), while the apoptotic rate was increased (3.8% vs. 8.1%). Conclusion: NOX4 can inhibit radiosensitivity of nasopharyngeal carcinoma cells possibly by activating PI3K/AKT pathway.

AKT-GSK3ß Signaling Pathway Regulates Mitochondrial Dysfunction-Associated OPA1 Cleavage Contributing to Osteoblast Apoptosis: Preventative Effects of Hydroxytyrosol.

Oxidative stress (OS) induces osteoblast apoptosis, which plays a crucial role in the initiation and progression of osteoporosis. Although OS is closely associated with mitochondrial dysfunction, detailed mitochondrial mechanisms underlying OS-induced osteoblast apoptosis have not been thoroughly elucidated to date. In the present study, we found that mitochondrial abnormalities largely contributed to OS-induced osteoblast apoptosis, as evidenced by enhanced production of mitochondrial reactive oxygen species; considerable reduction in mitochondrial respiratory chain complex activity, mitochondrial membrane potential, and adenosine triphosphate production; abnormality in mitochondrial morphology; and alteration of mitochondrial dynamics. These mitochondrial abnormalities were primarily mediated by an imbalance in mitochondrial fusion and fission through a protein kinase B- (AKT-) glycogen synthase kinase 3ß- (GSK3ß-) optic atrophy 1- (OPA1-) dependent mechanism. Hydroxytyrosol (3,4-dihydroxyphenylethanol (HT)), an important compound in virgin olive oil, significantly prevented OS-induced osteoblast apoptosis. Specifically, HT inhibited OS-induced mitochondrial dysfunction by decreasing OPA1 cleavage and by increasing AKT and GSK3ß phosphorylation. Together, our results indicate that the AKT-GSK3ß signaling pathway regulates mitochondrial dysfunction-associated OPA1 cleavage, which may contribute to OS-induced osteoblast apoptosis. Moreover, our results suggest that HT could be an effective nutrient for preventing osteoporosis development.

[Clinical value of fluorescence in situ hybridization positive of exfoliated urothelial cells in urothelial carcinoma].

OBJECTIVE: To analyze the clinical pathologic characteristics of cases with fluorescence in situ hybridization (FISH) positive of exfoliated urothelial cells, so as to evaluate the clinical utility of FISH in the diagnosis of urothelial carcinoma (UC). METHODS: A total of 271 cases of FISH positive in Department of Urology of Peking University First Hospital from Apr. 2012 to Sep. 2015 were recruited in this study. Retrospective analysis was made on their clinical data. For FISH analysis, labeled probes specific for chromosomes 3, 7, 17, and the p16 (9p21) gene were used to assess chromosomal abnormalities indicative of malignancy. The positive predict values (PPV) of all the techniques were analyzed. RESULTS: Of the 271 patients, 207 cases were UC, 7 cases were non-UC, and 57 cases were benign diseases. The PPV of FISH in detecting UC was 76.4%, while the 95% confidence interval (CI) 71.3% to 81.5%. In the cohort of FISH positive, this value was similar to that of urinary cytology (PPV 86.8%, 95% CI: 78.5%-95.0%). The PPV of FISH was lower than that of cystoscopy and ureteroscopy (PPV 96.1%, 95% CI: 91.7%-100.0%). There were significant differences between this study and the PPV of FISH reported abroad (PPV 53.9%, χ2=33.048, P<0.001). Of all the UC with FISH positive, bladder cancer showed an earlier pathological stage versus renal pelvic carcinoma and ureteral carcinoma, with significance (χ2=5.894, P=0.015, and χ2=13.601, P<0.001, respectively). However, no difference was found in the size, pathological stage and pathological grade of tumors between the urinary cytology positive group and the urinary cytology negative group. The rate of high-grade UC in ureteral carcinoma of FISH positive was 92.3%, much higher than that of ureteral carcinoma reported domestically. CONCLUSION: The PPV of FISH in detecting UC is higher relatively, with a better clinic value for Chinese patients. The ureteral carcinoma with FISH positive obtains a higher pathological grade, which is of great guiding significance for UC.

[Concurrent renal cell carcinoma and urothelial carcinoma: long-term follow-up study of 24 cases].

Objective: To investigate the clinical manifestation, diagnosis, treatment and outcome of simultaneous occurrence of renal cell carcinoma and urothelial carcinoma. Methods: Twenty-four consecutive patients with synchronous renal cell carcinoma and urothelial carcinoma treated in our center from March 2005 to December 2015 were retrospectively reviewed. Their clinical, pathological and prognostic features were evaluated. Kaplan-Meier curves were used to estimate overall survival. Results: Patient' age was range from 48 to 79 yrs (median 69.5). Fourteen patients presented with macroscopic hematuria, and 10 patients were asymptomatic. B-ultrasound, computed tomography (CT) and cystoscopy initially indicated renal cell carcinoma concurrent with ipsilateral upper urinary tract urothelial carcinoma (UTUC) in 4 cases, renal cell carcinoma concurrent with bladder tumor in 16 cases, renal cell carcinoma concurrent with both ipsilateral UTUC and bladder tumor in 1 case, renal cell carcinoma in 2 cases and ureter carcinoma in 1 case. Different treatments were performed. The median follow-up time after surgery was 22.5 months. For patients with synchronous renal cell carcinoma and bladder tumor, there was no significant survival difference between patients treated with partial nephrectomy or radical nephrectomy. During follow up, 3 patients died of renal cell carcinoma, 3 patients died of non-oncological disease and 1 patient died of ureter carcinoma. The 3-year overall survival rate was 82.7%. For patients with synchronous renal cell carcinoma and bladder tumor, there was no significant survival difference between patients treated with partial nephrectomy or radical nephrectomy (P=0.874). Conclusions: Concurrence of renal cell carcinoma and urothelial carcinoma is clinically rare. Treatments should be individualized. The prognosis for a patient with synchronous renal cell carcinoma and urothelial carcinoma is associated with the more aggressive one.

[Clinical significance of residual tumors at repeat transurethral resection in patients with T1 bladder cancer].

OBJECTIVE: To investigate the predictors of residual tumors at repeat transurethral resection of bladder tumors (re-TURBT) for the patients with T1 bladder cancer and evaluate the effect of the residual tumors on the prognosis of the disease. METHODS: We reviewed the clinical data of the patients with T1 bladder cancer who underwent re-TURBT from 2008 to 2015 in our department. Seventy-two patients received re-TURBT 2-6 weeks after the initial TURBT. A total of 65 patients were followed up, and we recorded the events of tumor recurrence, tumor progression, radical cystectomy and cancer specific death.The influencing factors of re-TURBT positive rate were analyzed.The effects of re-TURBT positive or negative findings on the prognosiswere compared. RESULTS: 33.3% of the patients who received re-TURBT had residual tumours. Re-TURBT positive in T1 bladder cancer has significant correlation with tumor size (P<0.05). Residual tumors tended to be detected in patients with larger tumors (diameter ≥ 4 cm) but might have no relationship with tumor grade or tumor number. The recurrence rate within 3 month ofthe patients with residual tumours at re-TURBT was 25% (5/20), while there were no patients suffering recurrence who had no residual tumours at re-TURBT, which had a significant difference (P<0.001). However, the overall recurrence rate, progression rate, rate of radical cystectomy and cancer specific mortality showed no significant difference between the two groups (45% vs 40%, P=0.71; 10% vs 6.7%, P=0.64; 5% vs 8.9%, P=0.59; 5% vs 2.2%, P=0.55). CONCLUSIONS: For the patients with T1 bladder cancer, larger tumors could be a predictor for residual tumors at re-TURBT. The presence of residual tumors is associated with early recurrence.

Triidothyronine and epinephrine rapidly modify myocardial substrate selection: a (13)C isotopomer analysis.

Triiodothyronine (T(3)) exerts direct action on myocardial oxygen consumption (MVO(2)), although its immediate effects on substrate metabolism have not been elucidated. The hypothesis, that T(3) regulates substrate selection and flux, was tested in isovolumic rat hearts under four conditions: control, T(3) (10 nM), epinephrine (Epi), and T(3) and Epi (TE). Hearts were perfused with [1,3-(13)C]acetoacetic acid (AA, 0.17 mM), L-[3-(13)C]lactic acid (LAC, 1.2 mM), U-(13)C-labeled long-chain free fatty acids (FFA, 0.35 mM), and unlabeled D-glucose (5.5 mM) for 30 min. Fractional acetyl-CoA contribution to the tricarboxylic acid cycle (Fc) per substrate was determined using (13)C NMR and isotopomer analysis. Oxidative fluxes were calculated using Fc, the respiratory quotient, and MVO(2). T(3) increased (P < 0.05) Fc(FFA), decreased Fc(LAC), and increased absolute FFA oxidation from 0.58 +/- 0.03 to 0.68 +/- 0.03 micromol. min(-1). g dry wt(-1) (P < 0.05). Epi decreased Fc(FFA) and Fc(AA), although FFA flux increased from 0.58 +/- 0.03 to 0.75 +/- 0.09 micromol. min(-1). g dry wt(-1). T(3) moderated the change in Fc(FFA) induced by Epi. In summary, T(3) exerts direct action on substrate pathways and enhances FFA selection and oxidation, although the Epi effect dominates at a high work state.

Human cardiac myosin heavy chain isoforms in fetal and failing adult atria and ventricles.

The goal of this study was to test the hypothesis that the relative amounts of the cardiac myosin heavy chain (MHC) isoforms MHC-alpha and MHC-beta change during development and transition to heart failure in the human myocardium. The relative amounts of MHC-alpha and MHC-beta in ventricular and atrial samples from fetal (gestational days 47--110) and nonfailing and failing adult hearts were determined. The majority of the fetal right and left ventricular samples contained small relative amounts of MHC-alpha (mean < 5% of total MHC). There was a small significant decrease in the level of MHC-alpha in the ventricles between 7 and 12 wk of gestation. Fetal atria expressed predominantly MHC-alpha (mean > 95%), with MHC-beta being detected in most samples. The majority of adult nonfailing right and left ventricular samples had detectable levels of MHC-alpha ranging from 1 to 10%. Failing right and left ventricles expressed a significantly lower level of MHC-alpha. MHC-alpha comprised approximately 90% of the total MHC in adult nonfailing left atria, whereas the relative amount of MHC-alpha in the left atria of individuals with dilated or ischemic cardiomyopathy was approximately 50%. The differences in MHC isoform composition between fetal and nonfailing adult atria and between fetal and nonfailing adult ventricles were not statistically significant. We concluded that the MHC isoform compositions of fetal human atria are the same as those of nonfailing adult atria and that the ventricular MHC isoform composition is different between adult nonfailing and failing hearts. Furthermore, the marked alteration in atrial MHC isoform composition, associated with cardiomyopathy, does not represent a regression to a pattern that is uniquely characteristic of the fetal stage.

Thyroid hormone coordinates respiratory control maturation and adenine nucleotide translocator expression in heart in vivo.

BACKGROUND: The signal transduction mechanism linking mitochondrial ATP synthesis with cytosolic ATP utilization in heart changes during postnatal development in vivo. This maturational process occurs in parallel with accumulation of mitochondrial adenine nucleotide translocator (ANT), which provides a possible site for respiratory control. We postulated that thyroid hormone regulates these maturational processes. METHODS AND RESULTS: We used (31)P MR spectroscopy to determine the relationship between myocardial high-energy phosphates, phosphocreatine, and ADP and oxygen consumption (MVO(2)) during epinephrine stimulation in 32- to 40-day-old lambs thyroidectomized after birth (THY) and age-matched controls. Steady-state protein and mRNA levels for ANT isoforms and beta-F(1)-ATPase were assessed from left ventricular tissues by Western and Northern blotting. With greater doses of epinephrine, THY attained lower peak MVO(2) than controls (P:<0.05). Controls maintained high-energy phosphate levels, unlike THY, which demonstrated significantly decreased phosphocreatine/ATP and increased cytosolic ADP despite lower peak MVO(2). No significant differences in beta-F(1)-ATPase protein or mRNA occurred between groups. However, ANT isoform mRNA levels were 2-fold greater and protein levels 4-fold greater in control hearts. CONCLUSIONS: These data imply that the maturational shift away from ADP-mediated respiratory control is regulated by thyroid hormone in vivo. Specific thyroid-modulated increases in ANT mRNA and protein imply that this regulation occurs in part at a pretranslational level.

Triiodothyronine repletion in infants during cardiopulmonary bypass for congenital heart disease.

OBJECTIVE: Cardiopulmonary bypass suppresses circulating thyroid hormone levels. Although acute triiodothyronine repletion has been evaluated in adult patients after cardiopulmonary bypass, triiodothyronine pharmacokinetics and effects have not previously been studied in infants undergoing operations for congenital heart disease. We hypothesized that triiodothyronine deficiency in the developing heart after bypass may adversely affect cardiac function reserve postoperatively. METHODS: Infants less than 1 year old undergoing ventricular septal defect or tetralogy of Fallot repair were randomized into 2 groups. Group T (n = 7) received triiodothyronine (0.4 microg/kg) immediately before the start of cardiopulmonary bypass and again with myocardial reperfusion. Control (NT, n = 7) patients received saline solution placebo or no treatment. RESULTS: These groups underwent similar ischemic and bypass times and received similar quantities of inotropic agents after the operation. The NT group demonstrated significant depression in circulating levels, compared with prebypass levels, for free triiodothyronine and total triiodothyronine at 1, 24, and 72 hours after bypass. Group T demonstrated similar low thyroxine values, but free and total triiodothyronine levels were maintained at prebypass levels for 24 hours and remained elevated over those of group NT (P <.05) at 72 hours. Heart rate was transiently elevated in group T compared with group NT (P <.05), and peak systolic pressure-rate product increased after 6 hours. CONCLUSION: These data imply that (1) triiodothyronine in the prescribed dose prevents circulating triiodothyronine deficiencies and (2) triiodothyronine repletion promotes elevation in heart rate without concomitant decrease in systemic blood pressure. Elevation of peak systolic pressure-rate product implies that triiodothyronine repletion improves myocardial oxygen consumption and may enhance cardiac function reserve after cardiopulmonary bypass in infants.

Signaling and expression for mitochondrial membrane proteins during left ventricular remodeling and contractile failure after myocardial infarction.

OBJECTIVES: This study was conducted to test hypotheses stating that: 1) altered signaling for mitochondrial membrane proteins occurs during postinfarction remodeling, and 2) successful myocardial adaptation relates to promotion of specific mitochondrial membrane components. BACKGROUND: Abnormalities in high-energy phosphate content and limitations in adenosine 5'-triphosphate (ATP) synthesis rate occur during the transition to contractile failure from compensatory remodeling after left ventricular infarction. The adenine nucleotide translocator (ANT) and F1-ATPase respectively regulate mitochondrial adenosine 5'-diphosphate (ADP)/ATP exchange and ADP-phosphorylation, which are key components of high-energy phosphate metabolism. METHODS: Steady-state mRNA and protein expression for ANT isoform1 and the beta subunit of the F1-ATPase (betaF1) were analyzed in myocardium remote from the infarction zone eight weeks after left circumflex coronary artery ligation in pigs, demonstrating either successful left ventricular remodeling (LVR, n = 8) or congestive heart failure (CHF, n = 4) as determined by clinical and contractile performance parameters. RESULTS: Substantial reductions in steady-state mRNA expression for ANT1 and betaF1 relative to normal (n = 8) occur in CHF, p < 0.01, but not in LVR. Relative expression for both proteins coordinated with their respective steady-state mRNA levels; CHF at 40% normal, p < 0.05 for ANT and 70% normal for betaF1, p < 0.05. CONCLUSIONS: Maintained signaling for major mitochondrial membrane proteins occurs in association with successful remodeling and adaptation after infarction. Reduced expression of these proteins relates to limited ATP synthesis capacity and high energy phosphate kinetic abnormalities previously demonstrated in CHF. These findings imply that mitochondrial processes participate in myocardial remodeling after infarction.

Mitochondrial protein and HSP70 signaling after ischemia in hypothermic-adapted hearts augmented with glucose.

Hypothermia improves resistance to subsequent ischemia in the cardioplegic-arrested heart (CAH). This adaptive process produces mRNA elevation for heat shock protein (HSP) 70-1 and mitochondrial proteins, adenine nucleotide translocator (ANT(1)), and beta-F(1)-ATPase. Glucose in cardioplegia also enhances myocardial protection. These processes might be linked to reduced ATP depletion. To assess for synergism between these protective processes, isolated rabbit hearts (n = 91) were perfused at 37 degrees C and exposed to ischemic cardioplegic arrest for 2 h. Hearts were in four groups: control (C), hypothermia adapted (H) perfused to 31 degrees C 20 min before ischemia, 22 mM glucose (G) in cardioplegia, and hypothermic adaptation and glucose (HG). Developed pressure (DP), dP/dt(max), and pressure-rate product (PRP) improved (P < 0.05) in G, H, and HG compared with C during reperfusion. DP and PRP were elevated in HG over H and G. ATP was higher in G, H, and HG, although no additional increase in HG over H was found. Lactate and CO(2) production were elevated in G only. The mRNA expression for HSP70-1, ANT(1), and beta-F(1)-ATPase was elevated severalfold in H and HG, but not G over C during reperfusion. In conclusion, glucose provides additional functional improvement in H. Additionally, neither ATP levels nor anaerobic metabolism are linked to mRNA expression for HSP70, ANT(1), or beta-F(1)-ATPase in CAH.

Maturational changes in gene expression for adenine nucleotide translocator isoforms and betaF1-ATPase in rabbit heart.

Maturational changes in myocardial respiratory control have been related to postnatal accumulation of adenine nucleotide translocator (ANT) in the inner mitochondrial membrane. Alternatively alterations in relative isoform distribution for this nuclear-encoded gene during myocardial maturation might be responsible for changing the kinetics of respiratory control. Rabbit hearts were analyzed for adenine nucleotide translocator isoform (ANT1, ANT2, ANT3) gene expression and distribution at four ages (fetal, 29/31 days of gestation; 1 h postnatal; 9 days postnatal; and 3-4 months postnatal). Transcript levels for the coordinately expressed betaF1-ATPase were also examined in these hearts. These studies demonstrated that mRNA expression for ANT1 in coordination with betaF1-ATPase increased substantially after 9 days of age in rabbit hearts. Expression of the minor isoform ANT3 parallels ANT1, though no change in expression of the kidney-specific isoform ANT2 occurs in heart during this developmental period. Previous work has demonstrated that ANT protein accumulation is closely coordinated with mRNA expression for ANT1. These results support previous studies, which indicate that the operational mode of myocardial respiratory control depends on adenine nucleotide mRNA expression. Changes in relative adenine nucleotide translocator isoform distribution do occur during fetal to mature transition and may contribute to observed changes in the mode of respiratory control.

Temperature threshold and preservation of signaling for mitochondrial membrane proteins during ischemia in rabbit heart.

Temperature modulates both myocardial energy requirements and production. We have previously demonstrated that myocardial protection induced by hypothermic adaptation preserves expression of genes regulating heat shock protein and the nuclear-encoded mitochondrial proteins, the adenine nucleotide translocator isoform 1 (ANT1), and the beta subunit of F1-ATPase (beta F1-ATPase). This preservation is associated with a reduction in ATP depletion similar to that noted in cardioplegic arrested hearts preserved at a critical temperature (30 degrees C) or below. We tested the hypothesis that expression of these genes may also be subject to this temperature threshold phenomenon. Isolated perfused rabbit hearts were subjected to ischemic cardioplegic arrest at 4, 30, or 34 degrees C for 120 min. Cardiac function indices and steady-state mRNA levels for ANT1, beta F1-ATPase, and HSP70-1 were measured prior to ischemia (B) and after 45 min of reperfusion. Cardiac function was significantly depressed in the 34 degrees C group. Ischemia at 34 degrees C reduced steady-state mRNA levels for ANT1 and beta F1-ATPase from B, but these levels were similarly preserved at 4 and 30 degrees C. HSP70-1 levels were mildly elevated (fourfold) above B to similar levels at all three temperatures. These results indicate that mRNA expression for ANT1 and beta F1-ATPase is specifically preserved in a pattern consistent with the temperature threshold phenomenon. HSP70-1 expression is not influenced by ischemic temperature. Preservation of gene expression for these mitochondrial proteins implies that signaling for mitochondrial biogenesis or resynthesis is maintained after ischemic insult.

Hypothermia preserves function and signaling for mitochondrial biogenesis during subsequent ischemia.

Hypothermia is known to protect myocardium during ischemia, but its role in induction of a protective stress response before ischemia has not been evaluated. As cold incites stress responses in other tissues, including heat shock protein induction and signaling mitochondrial biogenesis, we postulated that hypothermia in perfused hearts would produce similar phenomena while reducing injury during subsequent ischemia. Studies were performed in isolated perfused rabbit hearts (n = 77): a control group (C) and a hypothermic group (H) subjected to decreasing infusate temperature from 37 to 31 degrees C over 20 min. Subsequent ischemia during cardioplegic arrest at 34 degrees C for 120 min was followed by reperfusion. At 15 min of reperfusion, recovery of left ventricular developed pressure (LVDP), maximum first derivative of left ventricular pressure (LV dP/dtmax), LV -dP/dtmax, and the product of heart rate and LVDP was significantly increased in H (P < 0.01) compared with C hearts. Ischemic contracture started later in H (97.5 +/- 3.6 min) than in C (67.3 +/- 3.3 min) hearts. Myocardial ATP preservation and repletion during ischemia and reperfusion were higher in H than in C hearts. mRNA levels of the nuclear-encoded mitochondrial proteins adenine nucleotide translocase isoform 1 (ANT1) and beta-F1-adenosine-triphosphatase (beta-F1-ATPase) normalized to 28S RNA decreased in C hearts but were preserved in H hearts after reperfusion. Inducible heat shock protein (HSP70-1) mRNA was elevated nearly 4-fold after ischemia in C hearts and 12-fold in H hearts. These data indicate that hypothermia preserves myocardial function and ATP stores during subsequent ischemia and reperfusion. Signaling for mitochondrial biogenesis indexed by ANT1 and beta-F1-ATPase mRNA levels is also preserved during a marked increase in HSP70-1 mRNA.

Temperature threshold and modulation of energy metabolism in the cardioplegic arrested rabbit heart.

Hypothermia protects ischemic tissues by reducing ATP utilization and accumulation of harmful metabolites. However, it also reduces ATP production, which might cause deterioration in the energy supply/demand ratio. Modulation of energy supply/demand according to temperature has not been previously studied in detail. In this study, isolated, perfused rabbit hearts (n = 60) were used to determine the effects of various temperatures on myocardial energy metabolism and function during cardioplegic arrest. Ischemia was induced by crystalloid cardioplegic solution at 4, 18, 30, and 34 degrees C for 120 min, respectively. At each temperature, the hearts were divided into a glucose-treated group which contained 22 mM glucose in cardioplegic solution as the only substrate and a control group which contained 22 mM mannitol to keep same osmolarity. Following 15 min reperfusion, recovery of left ventricular developed pressure (DP), +/- dP/dtmax, and the product of heart rate and DP were significantly higher in 30, 18, and 4 degrees C groups than those in 34 degrees C control group. The functional recovery was also significantly higher in the 34 degrees C glucose-treated group than that in the 34 degrees C control group, but there was no difference between those groups at 30 degrees C and the temperature below 30 degrees C. Myocardial ATP concentration was significantly lower in 34 degrees C control group than those in other groups. There is a close relationship between myocardial ATP concentration and functional recovery (R2 = 0.90). The accumulations of lactate and CO2 were significantly higher at 34 degrees C in glucose-treated group than those in the control group. However, there was no significant difference between these two groups at 30 degrees C and the temperature below 30 degrees C. These results indicate that under these study conditions: (1) a marked decrease in energy supply/demand occurs above 30 degrees C, implying that a temperature threshold exists; and (2) this can be ameliorated by provision of glucose as substrate in cardioplegia solution.

Expression of adenine nucleotide translocator parallels maturation of respiratory control in heart in vivo.

Changes in the relationship between myocardial high-energy phosphates and oxygen consumption in vivo occur during development, implying that the mode of respiratory control undergoes maturation. We hypothesized that these maturational changes in sheep heart are paralleled by alterations in the adenine nucleotide translocator (ANT), which are in turn related to changes in the expression of this gene. Increases in myocardial oxygen consumption (MVO2) were induced by epinephrine infusion in newborn (0-32 h, n = 6) and mature sheep (30-32 days, n = 6), and high-energy phosphates were monitored with 31P nuclear magnetic resonance. Western blot analyses for the ANT1 and the beta-subunit of F1-adenosinetriphosphatase (ATPase) were performed in these hearts and additional (n = 9 total per group) as well as in fetal hearts (130-132 days of gestation, n = 5). Northern blot analyses were performed to assess for changes in steady-state RNA transcripts for these two genes. Kinetic analyses for the 31P spectra data revealed that the ADP-MVO2 relationship for the newborns conformed to a Michaelis-Menten model but that the mature data did not conform to first- or second-order kinetic control of respiration through ANT. Maturation from fetal to mature was accompanied by a 2.5-fold increase in ANT protein (by Western blot), with no detectable change in beta-F1-ATPase. Northern blot data show that steady-state mRNA levels for ANT and beta-F1-ATPase increased approximately 2.5-fold from fetal to mature. These data indicate that 1) respiratory control pattern in the newborn is consistent with a kinetic type regulation through ANT, 2) maturational decreases in control through ANT are paralleled by specific increases in ANT content, and 3) regulation of these changes in ANT may be related to increases in steady-state transcript levels for its gene.

Influence of the pH of cardioplegic solutions on cellular energy metabolism and hydrogen ion flux during neonatal hypothermic circulatory arrest and reperfusion: a dynamic 31P nuclear magnetic resonance study in a pig model.

OBJECTIVES: The pH of cardioplegic solutions is postulated to affect myocardial protection during neonatal hypothermic circulatory arrest. Neither optimization of cardioplegic pH nor its influence on intracellular pH during hypothermic circulatory arrest has been previously studied in vivo. Thus we examined the effects of the pH of cardioplegic solutions on postischemic cardiac function in vivo, including two possible operative mechanisms: (1) reduction in adenosine triphosphate use and depletion of high-energy phosphate stores or (2) reduction of H+ flux during reperfusion, or both. METHODS: Dynamic 31P spectroscopy was used to measure rates of adenosine triphosphate use, high-energy phosphate depletion, cytosolic acidification during hypothermic circulatory arrest, and phosphocreatine repletion and realkalinization during reperfusion. Neonatal pigs in three groups (n = 8 each)--group A, acidic cardioplegia (pH = 6.8); group B, basic cardioplegia (pH = 7.8); and group N, no cardioplegia--underwent hypothermia at 20 degrees C with 60 minutes of hypothermic cardioplegia followed by reperfusion. RESULTS: Recoveries of peak elastance, stroke work, and diastolic stiffness were superior in group B. Indices of ischemic adenosine triphosphate use, initial phosphocreatine depletion rate, and tau, the exponential decay half-time, were not different among groups. Peak [H+] in group A (end-ischemia) was significantly elevated over that of group B. The realkalinization rate was reduced in group B compared with that in groups A (p = 0.015) and N (p = 0.035), with no difference between groups A and N (p = 0.3). Cytosolic realkalinization rate was markedly reduced and the half-time of [H+] decay was increased during reperfusion in group B. CONCLUSIONS: Superior postischemic cardiac function in group B is not related to alterations in ischemic adenosine triphosphate use or high-energy store depletion, but may be due to slowing in H+ efflux during reperfusion, which should reduce Ca++ and Na+ influx.

Hypoxic pHi and function modulation by Na+/H+ exchange and alpha-adrenoreceptor inhibition in heart in vivo.

Regulation of intracellular pH (pHi) may contribute to maintenance of cardiac contractile function during graded hypoxia in vivo. To test this hypothesis, we disturbed pHi regulation in vivo using two approaches: alpha-adrenoreceptor antagonism with phentolamine (1 mg/kg) (Phen; n = 9); and Na+/H+ exchange inhibition with HOE-642 (2 mg/kg; n = 6) before graded hypoxia in open-chest sheep. Hemodynamic parameters including left ventricular maximal pressure development (dP/dtmax) cardiac index (CI), and left ventricular power were monitored continuously and simultaneously with high-energy phosphate levels and pHi, measured with 31P nuclear magnetic resonance spectroscopy in Phen, HOE-642, and control (Con; n = 9). In subgroups (n = 6) in Con and Phen, coronary flow, myocardial oxygen consumption (MVO2), and lactate uptake were also measured. During hypoxia, the functional parameters left ventricular dP/dtmax, CI, and left ventricular power decreased significantly compared with baseline and Con values. These decreases were preceded by a significant drop (P < 0.05) in pHi from 7.10 +/- 0.04 to 6.69 +/- 0.05 in Phen and corresponded temporally to a pHi drop from 7.10 +/- 0.02 to 6.77 +/- 0.03 in HOE-642. Decreases in pHi in Phen were not preceded by decreases in cardiac function or MVO2. In contrast, cardiac function parameters increased significantly in Con, whereas no significant pHi decrease occurred (7.07 +/- 0.03 to 6.98 +/- 0.04). We conclude that these data indicate that pHi regulation can be disrupted through alpha-adrenergic antagonism or Na+/H(+)-exchange inhibition in vivo. These studies demonstrate that pHi regulation performs a role in the modulation of cardiac function during hypoxia in vivo.