Female Rat Hearts Research Articles

Overexpression of Inducible Nitric Oxide Synthase Impairs the Survival of Bone marrow Stem Cells Transplanted into Rat Infarcted Myocardium

AimsInducible nitric oxide synthase (iNOS) over-expression is considered critical to the death of transplanted cells in infarcted myocardium. The present study was to investigate the effect of iNOS on the survival of transplanted bone marrow mesenchymal stem cells (BMSCs) in infarcted myocardium. Main methods and key findingsMale rat BMSCs were injected into the infarct region of female rat hearts at 1hour (H1, group A), day 3 (D3, group B), and day 7 (D7, group C) after coronary artery ligation, and harvested on D7 after transplantation. Myocardial iNOS expression was significantly increased shortly after coronary ligation with its peak on D3, and returned to baseline at D7. The cell survival rates were 6.2%, 2.1%, and 8.3% in group A, B, and C, respectively, one week after transplantation as assessed by detecting the Y-chromosome sry sequence in the infarct region. There was no significant difference in the survival rates between D7 and week 6 after cell transplantation in group A. Treating the animals in group B with the selective iNOS inhibitor 1400W significantly increased the survival rate (from 1.8% to 4.2%). Apoptosis level of the transplanted cells was also significantly reduced with 1400W treatment in group B. SignificanceBMSC transplantation on H1 and D7 after coronary ligation might be the optimal time for cell survival. The loss of transplanted BMSCs in the infarcted myocardium was partially due to increased apoptosis and iNOS overexpression. Selective iNOS inhibition early in myocardial infarction may increase the cell viability.

An Evaluation of Lipid Profile and Antioxidant Activities of <i>Carica Papaya</i> Seed Oil in the Heart and Liver of Female Wistar Rats.

Increasing attention is been given to Carica papaya seed due to its oil rich nature, and its medicinal value. Four feed diets consisting of 3, 5, 7, and 10 % of the oil were composed and examined for its in-vivo effect on lipid and antioxidants status of female wistar rats compared to those fed with 5 % groundnut oil based diet. The feeds were fed into the rats for 32 days, and examined for their lipid profile and antioxidant status in the liver and heart. Free fatty acids were significantly reduced (P<0.05) by 3-10 % diets in the liver, and by 10 % diet in the heart. HMG-CoA/Mevalonate ratio in the liver was significant increased (P<0.05) by the 7-10 % diets. All diets significantly increased (P<0.05) superoxide dismutase, peroxidase, and reduced glutathione in liver. Lipid peroxidation in the heart was significantly increased (P<0.05) by the 3-7 % diets. Lipid peroxidation, and phospholipid in heart were significantly reduced, and increased (P<0.05) respectively by 10 % diets. The biochemical status of rats fed with the Carica papaya seed oil based diets generally remained comparable to those fed with the groundnut oil diet in the two organs. The Carica papaya seed oil exhibited better antioxidant activities, and health benefits than the commonly consumed groundnut oil.Key words: - Carica papaya; Seeds; Oil, Quality; Antioxidants; Lipids.

Effects of melatonin and epiphyseal proteins on fluoride-induced adverse changes in antioxidant status of heart, liver, and kidney of rats.

Several experimental and clinical reports indicated the oxidative stress-mediated adverse changes in vital organs of human and animal in fluoride (F) toxicity. Therefore, the present study was undertaken to evaluate the therapeutic effect of buffalo (Bubalus bubalis) epiphyseal (pineal) proteins (BEP) and melatonin (MEL) against F-induced oxidative stress in heart, liver, and kidney of experimental adult female rats. To accomplish this experimental objective, twenty-four adult female Wistar rats (123–143 g body weights) were divided into four groups, namely, control, F, F + BEP, and F + MEL and were administered sodium fluoride (NaF, 150 ppm elemental F in drinking water), MEL (10 mg/kg BW, i.p.), and BEP (100 µg/kg BW, i.p.) for 28 days. There were significantly (P < 0.05) high levels of lipid peroxidation and catalase and low levels of reduced glutathione, superoxide dismutase, glutathione reductase, and glutathione peroxidase in cardiac, hepatic, and renal tissues of F-treated rats. Administration of BEP and MEL in F-treated rats, however, significantly (P < 0.05) attenuated these adverse changes in all the target components of antioxidant defense system of cardiac, hepatic, and renal tissues. The present data suggest that F can induce oxidative stress in liver, heart, and kidney of female rats which may be a mechanism in F toxicity and these adverse effects can be ameliorated by buffalo (Bubalus bubalis) epiphyseal proteins and melatonin by upregulation of antioxidant defense system of heart, liver, and kidney of rats.

The Effects of Aging on Indices of Oxidative Stress and Apoptosis in the Female Fischer 344/Nnia X Brown Norway/BiNia Rat Heart

Oxidative-nitrosative stress may play a role in age-associated cardiovascular disease as implied by recent studies.However, limited research has been conducted using aged female rodent models. In this study, we examined hearts obtained from 6-, 26-, and 30-month old female Fischer 344/Nnia x Brown Norway/BiNia (F344xBN) rats in order to examine how aging affects levels of cardiac oxidative-nitrosative stress and apoptosis. Oxidative (superoxide anion and 4-HNE) and nitrosative (protein nitrosylation) stress markers were increased 180 ± 17 %, 110 ± 3 %, and 14 ± 2 %, respectively in 30-month hearts compared to the hearts of 6-month female rats. Coincident with these changes in oxidative-nitrosative stress, aging was also found to be associated with increases in the number of Tdt-mediated dUTP nick labeling (TUNEL)-positive cardiomyocytes, alterations in the Bax/Bcl-2 ratio, and elevated cleavage of caspase-3. Regression analysis demonstrates significant correlation in the age-associated changes markers of oxidative–nitrosative stress with changes in apoptotic signaling. The findings from this descriptive study imply that age-associated increases in mitochondrial-mediated apoptosis may be associated with the increase in oxidative-nitrosative stress in the aging F344xBN female heart.

β‐Sitosterol Enhances Cellular Glutathione Redox Cycling by Reactive Oxygen Species Generated From Mitochondrial Respiration: Protection Against Oxidant Injury in H9c2 Cells and Rat Hearts

Herba Cistanches (Cistanche deserticola Y. C. Ma) is a 'Yang-invigorating' tonic herb in Chinese medicine. Preliminary chemical analysis indicated that β-sitosterol (BS) is one of the chemical constituents in an active fraction of Herba Cistanches. To investigate whether BS is an active ingredient of Herba Cistanches, the effects of BS on H9c2 cells and rat hearts were examined. The results indicated that BS stimulated the mitochondrial ATP generation capacity in H9c2 cells, which was associated with the increased production of mitochondrial reactive oxygen species. BS also stimulated mitochondrial state 3 and state 4 respiration, with the resultant decrease in coupling efficiency. BS produced an up-regulation of cellular glutathione redox cycling and protected against hypoxia/reoxygenation-induced apoptosis in H9c2 cells. However, the protective effect of BS against myocardial ischemia/reperfusion injury was seen in female but not male rats ex vivo. The cardioprotection afforded by BS was likely mediated by an up-regulation of mitochondrial glutathione redox cycling in female rat hearts. In conclusion, the ensemble of results suggests that BS is an active ingredient of Herba Cistanches. The gender-dependent effect of BS on myocardial protection will further be investigated.

Molecular Mechanisms Underlying the Rapid Arrhythmogenic Action of Bisphenol A in Female Rat Hearts

Previously we showed that bisphenol A (BPA), an environmental estrogenic endocrine disruptor, rapidly altered Ca(2+) handling and promoted arrhythmias in female rat hearts. The underlying molecular mechanism was not known. Here we examined the cardiac-specific signaling mechanism mediating the rapid impact of low-dose BPA in female rat ventricular myocytes. We showed that protein kinase A (PKA) and Ca(2+)/CaM-dependent protein kinase II (CAMKII) signaling pathways are the two major pathways activated by BPA. Exposure to 1 nM BPA rapidly increased production of cAMP and rapidly but transiently increased the phosphorylation of the ryanodine receptors by PKA but not by CAMKII. BPA also rapidly increased the phosphorylation of phospholamban (PLN), a key regulator protein of sarcoplasmic reticulum Ca(2+) reuptake, by CAMKII but not PKA. The increase in CAMKII phosphorylation of PLN was mediated by phospholipase C and inositol trisphosphate receptor-mediated Ca(2+) release, likely from the endoplasmic reticulum Ca(2+) storage. These two pathways are likely localized, impacting only their respective target proteins. The rapid impacts of BPA on ryanodine receptors and PLN phosphorylation were mediated by estrogen receptor-β but not estrogen receptor-α. BPA's rapid signaling in cardiac myocytes did not involve activation of ERK1/2. Functional analysis showed that PKA but not CAMKII activation contributed to BPA-induced sarcoplasmic reticulum Ca(2+) leak, and both PKA and CAMKII were necessary contributors to the stimulatory effect of BPA on arrhythmogenesis. These results provide mechanistic insight into BPA's rapid proarrhythmic actions in female cardiac myocytes and contribute to the assessment of the consequence and potential cardiac toxicity of BPA exposure.

Expression and Cellular Distribution of Glucose Transporters and Alpha Subunits of Na+/K+-ATPase in the Heart of Fructose-fed Female Rats: The Role of Estradiol

Remarkable parallels are observed between glucose transporters (GLUT) and subunits of Na+/K+-ATPase, which deal with insulin regulation, tissue specificity, intracellular distribution and function of these proteins. To test our hypothesis that similarities also exist in alteration of cardiac GLUTs and alpha subunit isoforms of the pump in insulin resistance, animal model of fructose rich diet was exploited. The role of estradiol in regulation of GLUTs and Na+/K+-ATPase in insulin resistance context was studied as well. Cardiac protein expression, as well as insulin-regulated cellular localization of GLUT4, GLUT1, and α1 and α2 subunits of the pump were analyzed by Western blot. Fructose rich diet increased plasma insulin level and HOMA index, while estradiol treatment reversed both parameters to the control level. We did not observe obvious similarities in the pattern of alterations of GLUT1/α1 subunit of the pump, as well as GLUT4/α2 subunit, related to diet or hormone treatment. Considering alterations in expression and cellular localization of GLUTs and the pump subunits, fructose rich diet jeopardized cardiac glucose transport in some extent, but in contrast, stimulated Na+/K+-ATPase function. Estradiol treatment opposed the fructose diet biochemical action and the effect on cardiac GLUTs, but was inefficient concerning the changes of cardiac Na+/K+-ATPase subunits. Changes of the cardiac molecules can be mediated by alterations in the level of insulin and nonesterified fatty acids, induced by the diet and hormone treatment.

The protective effects of 17beta-estradiol against ischemia–reperfusion injury and its effect on pacing postconditioning protection to the heart

The role of pacing postconditioning (PPC) in the heart protection against ischemia-reperfusion injury is not completely understood. The aim of this study was to investigated if 17-β-estradiol (estrogen, E2), endogenous atrial natriuretic peptide (ANP), endogenous brain natriuretic peptide (BNP), and tumor necrosis factor-alpha (TNF-α) are involved in PPC-mediated protection. Langendorff perfused female Wistar rat hearts were used for this study. Hearts challenged with regional ischemia for 30 min subjected to no further treatment served as a control. The PPC protocol was 3 cycles of 30 s pacing alternated between the right atrium and left ventricle (LV). Protection was assessed by recovery of LV contractility and coronary vascular-hemodynamics. Ischemia induced a significant (P < 0.05) deterioration in the heart function compared with baseline data. PPC alone or in combination with short-term E2 treatment (E2 infusion at the beginning of reperfusion) significantly (P < 0.05) improved the heart functions. Short-term E2 treatment post-ischemically afforded protection similar to that of PPC. However, long-term E2 substitution for 6 weeks completely attenuated the protective effects of PPC. Although no changes were noted in endogenous ANP levels, PPC significantly increased BNP expression level and decreased TNF-α in the cardiomyocyte lysate and coronary effluent compared to ischemia and controls. Our data suggested a protective role for short-term E2 treatment similar to that of PPC mediated by a pathway recruiting BNP and downregulating TNF-α. Our study further suggested a bad influence for long-term E2 substitution on the heart as it completely abrogated the protective effects of PPC.

Estrogens protect myocardium against ischemia/reperfusion insult by up-regulation of CRH receptor type 2 in female rats

BackgroundThe mechanism underlying estrogen cardioprotection remains largely unknown. Urocortin (UCN), a member of corticotropin-releasing hormone (CRH) family, is one of endogenous cardioprotective factors. The goal of present study is to investigate whether estrogens regulate UCN and its receptor CRH receptor type 2 (CRHR2) in female rat heart. Methods17β-estradiol (E2) was subcutaneously administrated to ovariectomized (OVX) rats for eight weeks. UCN was administrated before simulated myocardial ischemia/reperfusion (I/R). Cell damage was assessed by measurement of infarct size, activity of serum creatine kinase (CK) and lactate dehydrogenase (LDH) and percentage of TUNEL staining in myocardium. The mRNA and protein levels of UCN and CRHR2 were determined in sham operated and OVX rats with or without E2 replacement. DNA methylation frequency of CRHR2 gene promoter was determined by bisulfite-sequencing. ResultsUCN administration reduced infarct size, LDH and CK level and percentage of TUNEL staining upon I/R injury. The cardioprotective effects of UCN were abrogated in OVX rats and E2 replacement restored UCN-induced cardioprotection.CRHR2 mRNA and protein expression were down-regulated more than 40% in OVX rats, both of which were restored by E2 replacement. UCN mRNA and protein levels were not affected by ovariectomy and E2 replacement. Hypermethylation in CRHR2 promoter was found in OVX rats, and two of the methylated CpG sites were seated at cis-acting elements. Hypermethylation induced by OVX could also be ameliorated by E2 replacement. ConclusionEstrogens maintain CRHR2 expression in myocardium, which may through an epigenetic mechanism, and enhance UCN-induced cardioprotective effects against I/R injury.

Altered Mitochondrial Morphology Elucidates Cell Death Mechanisms in the Aged Female Rat Heart

BackgroundAcute myocardial infarction and associated ischemia/reperfusion (I/R) injury remains a leading cause of death in older post‐menopausal women. I/R injury triggers mitochondrial dysfunction leading to necrosis, apoptosis, and/or autophagy.PurposeTo determine if age‐associated estrogen deficiency alters mitochondrial morphology in conjunction with vulnerability to I/R injury.MethodsMitochondrial morphology was assessed through electron microscopy in border zone regions following coronary artery ligation (55 min I and 4–6 hr R) or sham in adult (6 mo) ovary‐intact, aged (24 mo) ovary‐intact and aged ovariectomized (OVX) female F344 rats. Necrosis was assessed by triphenyltetrazolium chloride staining, apoptosis by DNA laddering and TUNEL, and markers of autophagy by western blotting.ResultsLoss of mitochondrial matrix following I/R was greatest in aged OVX. Mitochondrial area was less in aged vs adult in conjunction with increased mitochondrial number and marked Z line streaming. Reduced DNA laddering and TUNEL, combined with increased beclin‐1 and cathepsinD in aged vs adult, further support a dominant role for necrosis underlying cell death in aged females (n=4–5/group).ConclusionMorphological alterations in mitochondria with aging are likely contributory in necrotic cell death mechanisms associated with I/R injury in post‐menopausal women.

Impact of age and sex on response to ischemic preconditioning in the rat heart: differential role of the PI3K–AKT pathway

Sex and aging represent important factors that determine morbidity and mortality due to cardiovascular diseases in the human population. This study aimed to investigate the impact of aging on the response to ischemia-reperfusion in male and female rat hearts, and to explore a potential role of the PI3K-Akt pathway in the cardioprotective effects of ischemic preconditioning (IPC) in the myocardium of younger and older adult males and females. Langendorff-perfused nonpreconditioned and preconditioned hearts of 12- and 18-week-old male and female Wistar rats were subjected to regional ischemia and reperfusion with or without prior perfusion with the PI3K inhibitor wortmannin for the evaluation of ischemia-induced arrhythmias and the size of myocardial infarction (infarct size; IS). Aging did not modify IS in both sexes; however, it markedly increased susceptibility to arrhythmias. Although IPC effectively reduced IS in males and females of both ages, only the hearts of males and 18-week-old females benefited from its antiarrhythmic effect. In the preconditioned 12-week-old females, but not the 18-week-old females, and in males of both ages, wortmannin blunted the anti-infarct effect of IPC. In conclusion, activation of the PI3K-Akt pathway plays an important role in protection against lethal injury conferred by IPC in males irrespective of age. The IS-limiting effect of IPC appears to be PI3K-Akt-dependent only in the 12-week-old females.

Low-dose bisphenol A and estrogen increase ventricular arrhythmias following ischemia–reperfusion in female rat hearts

Bisphenol A (BPA) is an environmental estrogenic endocrine disruptor that may have adverse health impacts on a range of tissue/systems. In previous studies, we reported that BPA rapidly promoted arrhythmias in female rodent hearts through alteration of myocyte calcium handling. In the present study we investigated the acute effects of BPA on ventricular arrhythmias and infarction following ischemia-reperfusion in rat hearts. Rat hearts were subjected to 20 min of global ischemia followed by reperfusion. In female, but not male hearts, acute exposure to 1 nM BPA, either alone or combined with 1 nM 17β-estradiol (E2), during reperfusion resulted in a marked increase in the duration of sustained ventricular arrhythmias. BPA plus E2 increased the duration ventricular fibrillation, and the duration of VF as a fraction of total duration of sustained ventricular arrhythmia. The pro-arrhythmic effects of estrogens were abolished by MPP combined with PHTPP, suggesting the involvements of both ERα and ERβ signaling. In contrast to their pro-arrhythmic effects, BPA and E2 reduced infarction size, agreeing with previously described protective effect of estrogen against cardiac infarction. In conclusion, rapid exposure to low dose BPA, particularly when combined with E2, exacerbates ventricular arrhythmia following IR injury in female rat hearts.

Susceptibility to ischemia-induced ventricular fibrillation in isolated female rat hearts varies moderately with estrous cycle stage

IntroductionThe vast majority of studies employing the isolated perfused rat heart model to study ischemic arrhythmias have used male rats only. The objective of this study was to determine the susceptibility to ischemia-induced ventricular fibrillation (VF) in isolated female rat hearts in each stage of the estrous cycle that corresponds with a different endogenous reproductive hormonal environment. MethodsHearts were isolated from female rats under pentobarbital anesthesia and perfused with modified Krebs solution containing 3mM K+. Experiments were grouped according to estrous cycle stage that was determined by prior vaginal lavage (n=10–13 per group). A group of male rat hearts was used as the control. Regional ischemia was induced by coronary ligation and maintained for 30min. The incidence of VF was determined from the ECG. ResultsThe incidence of VF in male hearts was 100%, while the incidence of VF in female hearts was also high but varied moderately with stage of the estrous cycle (diestrus 70%, metestrus 100%, proestrus 90%, estrus 69%; P>0.05). Compared to male hearts, the onset of VF was similar in all groups except for hearts excised from rats in proestrus, in which it was delayed. There was no difference between groups in an arrhythmia score, ischemic zone size, or baseline electrocardiographic or hemodynamic variables. DiscussionIn conclusion, the susceptibility of isolated female rat hearts to ischemic VF is comparable to that of male rat hearts, meaning that isolated female rat hearts can be used as controls in studies to assess antiarrhythmic drug efficacy. Since female rats can be used for isolated heart studies of ischemic VF, the need to cull female rats is reduced. However, the variation in VF susceptibility in female rat hearts that is associated with the different stages of the estrous cycle may affect statistical power that could potentially lead to Type II statistical errors. This problem can be prevented with careful randomization.

Side effect of metenolone enanthate on rats heart in puberty: Morphometrical study

The aim of this study was the investigation of effects of the metenolone enanthate (ME) that is used among athletes as doping and muscle amplifier, on hearts of male and female rats that are in puberty using morphometrical methods. A total of 36 rats which were divided into three separate groups (Experiment, ME; vehicle, PO; control, C) each consisting of 6 male and 6 female rats were used. 0.5 mg/kg metenolone enanthate was applied intraperitoneally into experiment subjects 5 times a week over a period of 4 weeks. At the end of experiment, rats were euthanized and their hearts were cut at the level of musculus papillaris after the fixation in formalin. Hearts were taken out and embedded in paraffin wax. Photos were taken at cut surfaces, and thickness, diameters and surface area levels were measured. Left ventriculus mass (LVM) and left ventriculus mass index (LVMI) were calculated. In the study LVM (p<0.005) and LVMI (p<0.05) were found to be significantly higher in the ME group in females whereas left ventricular lumen diameter (LVLD) were found to be significantly lower (p<0.05). Thus left ventricular hypertrophy development was observed. LVM and LVMI were found to be similar in ME and C groups among male rats and the highest level of these data were found in the group. LVM and LVMI were higher among females (p<0.006). In conclusion, it has been shown that the adverse effects of ME on heart were developing starting from puberty and resulting with the enlargement of the heart and left ventricular hypertrophy and especially among females this condition was more evident. It has also been discussed that the continuous use of drugs may further enhance this condition.

Effects of short-term administration of estradiol on reperfusion arrhythmias in rats of different ages

Little is known about age-related differences in short-term effects of estradiol on ischemia-reperfusion (I/R) insults. The present study was designed to evaluate the effects of short-term treatment with estradiol on reperfusion arrhythmias in isolated hearts of 6-7-week-old and 12-14-month-old female rats. Wistar rats were sham-operated, ovariectomized and treated with vehicle or ovariectomized and treated with 17β-estradiol (E2; 5 µg·100 g−1·day−1) for 4 days. Hearts were perfused by the Langendorff technique. Reperfusion arrhythmias, i.e., ventricular tachycardia and/or ventricular fibrillation, were induced by 15 min of left coronary artery ligation and 30 min of reperfusion. The duration and incidence of I/R arrhythmias were significantly higher in young rats compared to middle-aged rats (arrhythmia severity index: 9.4 ± 1.0 vs 3.0 ± 0.3 arbitrary units, respectively, P < 0.05). In addition, middle-aged rats showed lower heart rate, systolic tension and coronary flow. Four-day E2 treatment caused an increase in uterine weight. Although E2 administration had no significant effect on the duration of I/R arrhythmias in middle-aged rats, it induced a marked reduction in the rhythm disturbances of young rats accompanied by a decrease in heart rate of isolated hearts. Also, this reduction was associated with an increase in QT interval. No significant changes were observed in the QT interval of middle-aged E2-treated rats. These data demonstrate that short-term estradiol treatment protects against I/R arrhythmias in hearts of young female rats. The anti-arrhythmogenic effect of estradiol might be related to a lengthening of the QT interval.

SKA-31, a novel activator of SKCa and IKCa channels, increases coronary flow in male and female rat hearts

Endothelial SK(Ca) and IK(Ca) channels play an important role in the regulation of vascular function and systemic blood pressure. Based on our previous findings that small molecule activators of SK(Ca) and IK(Ca) channels (i.e. NS309 and SKA-31) can inhibit myogenic tone in isolated resistance arteries, we hypothesized that this class of compounds may induce effective vasodilation in an intact vascular bed, such as the coronary circulation. In a Langendorff-perfused, beating rat heart preparation, acute bolus administrations of SKA-31 (0.01-5 µg) dose-dependently increased total coronary flow (25-30%) in both male and female hearts; these responses were associated with modest, secondary increases in left ventricular (LV) systolic pressure and heart rate. SKA-31 evoked responses in coronary flow, LV pressure, and heart rate were qualitatively comparable to acute responses evoked by bradykinin (1 µg) and adenosine (10 µg). In the presence of apamin and TRAM-34, selective blockers of SK(Ca) and IK(Ca) channels, respectively, SKA-31 and bradykinin-induced responses were largely inhibited, whereas the adenosine-induced changes were blocked by ∼40%; TRAM-34 alone produced less inhibition. Sodium nitroprusside (SNP, 0.2 μg bolus dose) evoked changes in coronary flow, LV pressure, and heart rate were similar to those induced by SKA-31, but were unaffected by apamin + TRAM-34. The NOS inhibitor L-NNA reduced bradykinin- and adenosine-evoked changes, but did not affect responses to either SKA-31 or SNP. Our study demonstrates that SKA-31 can rapidly and reversibly induce dilation of the coronary circulation in intact functioning hearts under basal flow and contractility conditions.

Estrogen Differentially Affects Expression of Calcium Handling Genes in Female and Male Adult Cardiomyocytes

Premenopausal women have a lower risk of developing heart disease compared with postmenopausal women and age-matched men. However, the debate about whether estrogen is cardioprotective is ongoing due to conflicting results from basic science and clinical trials as well as signaling pathways that make interpretation of effects difficult. Calcium handling in the contracting cells of the heart, the cardiomyocytes, is one of the most important pathways involved in heart function. We sought to determine if calcium-handling genes are regulated by estrogen in a sexually dimorphic manner to explain differences in heart health between men and women. Cardiomyocytes were isolated from the hearts of healthy male and female rats and were treated with different doses of estrogen (300pM, 10nM). Expression of a set of calcium handling genes was then measured to determine the effect of estrogen. Our results demonstrate that estrogen differentially regulates calcium-handling genes in female and male cells, an effect that is also dose-dependent. To our knowledge, this is the first study to examine expression of this comprehensive set of calcium-handling genes in response to estrogen and to consider its effects separately on cardiomyocytes isolated from males and females.

The metabolic syndrome of fructose-fed rats: Effects of long-chain polyunsaturated ω3 and ω6 fatty acids. VI. Further post-mortem investigations

The present study documents the increases in systolic arterial blood pressure, plasma leptin concentration and kidney proliferating cell nuclear antigen index, as well as the decreases in glutathione reductase, superoxide dismutase and catalase enzymatic activities in the liver, heart, kidney, soleus muscle and visceral adipose tissue homogenates of female rats exposed for 8 weeks to a diet containing 64% (w/w) D-fructose instead of 64% starch. In the fructose-fed rats, the partial substitution of sunflower oil by either safflower oil or salmon oil often opposed the fructose-induced changes in these variables. The present results, thus, extend to these functional, hormonal and enzymatic parameters the knowledge that the dietary supply of long-chain polyunsaturated ω6 fatty acids, mainly C18:2ω6, and long-chain polyunsaturated ω3 fatty acids opposes the undesirable features of the fructose-induced metabolic syndrome, with salmon oil demonstrating particular efficacy.

Sex Differences in Postischemic Cardiac Dysfunction and Norepinephrine Overflow in Rat Heart

The purpose of this study is to elucidate the relationship between sex difference and norepinephrine (NE) release in the pathogenesis of myocardial ischemia/reperfusion (I/R) injury. Isolated male and female rat hearts were subjected to 40-minute global ischemia followed by 30-minute reperfusion. Compared with male hearts, I/R-induced cardiac dysfunction, such as decreased left ventricular developed pressure and dP/dtmax and increased left ventricular end diastolic pressure, was significantly attenuated in female hearts. An excessive NE overflow in the coronary effluent from the postischemic heart in females was much less than that in males. These sex differences were abolished by ovariectomy, but in vivo treatment with 17β-estradiol recovered it. This ameliorating effect of 17β-estradiol was not observed in the presence of nitric oxide (NO) synthase inhibitor N-nitro-L-arginine. When NOx (NO2/NO3) levels in the coronary effluent after onset of reperfusion were measured, reversed correlated relationships between NOx production and I/R-induced cardiac dysfunction, and NE overflow, were observed. These findings suggest that sex differences in the postischemic cardiac dysfunction are closely related to the NE overflow from the postischemic heart and that estrogen plays a key role in the cardioprotective effect against I/R injury in female rats, by suppressing NE release via the enhancement of NO production.

Quantitative proteomic analysis reveals novel mitochondrial targets of estrogen deficiency in the aged female rat heart

The incidence of myocardial infarction rises sharply at menopause, implicating a potential role for estrogen (E(2)) loss in age-related increases in ischemic injury. We aimed to identify quantitative changes to the cardiac mitochondrial proteome of aging females, based on the hypothesis that E(2) deficiency exacerbates age-dependent disruptions in mitochondrial proteins. Mitochondria isolated from left ventricles of adult (6 mo) and aged (24 mo) F344 ovary-intact or ovariectomized (OVX) rats were labeled with 8plex isobaric tags for relative and absolute quantification (iTRAQ; n = 5-6/group). Groups studied were adult, adult OVX, aged, and aged OVX. In vivo coronary artery ligation and in vitro mitochondrial respiration studies were also performed in a subset of rats. We identified 965 proteins across groups and significant directional changes in 67 proteins of aged and/or aged OVX; 32 proteins were unique to aged OVX. Notably, only six proteins were similarly altered in adult OVX (voltage-dependent ion channel 1, adenine nucleotide translocator 1, cytochrome c oxidase subunits VIIc and VIc, catalase, and myosin binding protein C). Proteins affected by aging were primarily related to cellular metabolism, oxidative stress, and cell death. The largest change occurred in monoamine oxidase-A (MAO-A), a source of oxidative stress. While acute MAO-A inhibition induced mild uncoupling in aged mitochondria, reductions in infarct size were not observed. Age-dependent alterations in mitochondrial signaling indicate a highly selective myocardial response to E(2) deficiency. The combined proteomic and functional approaches described here offer possibility of new protein targets for experimentation and therapeutic intervention in the aged female population.