Background Doxorubicin-induced cardiotoxicity is a worldwide problem. Vitamin D is a well-known beneficial vitamin for bone growth and calcium homeostasis but recently it is also known for its cardioprotective effects. The aim of this study is to investigate the potential protective role of vitamin D on the cardiac dysfunction induced by chronic doxorubicin exposure, and to throw more light on the possible underlying mechanism (s) for such effect. Materials and Methods: 70 female Albino-rats were divided into 4 groups; control group (C), Doxorubicin-treated group (Dox): given i.p. injection of Dox in a dose of 2.5 mg/kg body weight (cumulative dose: 15 mg/kg) over 3 weeks, vitamin Dsupplemented group (Vit D): given vitamin D by oral gavage in a dose of 500 IU/kg daily, 5 days a week, also for 3 weeks and the combined Doxorubicintreated+vitamin D-supplemented group (Dox+Vit D). At the end of the experiment, ECG was recorded and in vitro isolated heart study was performed on Langendoroff preparation to measure peak tension (PT), time to peak tension (TPT), half relaxation time (HRT) and myocardial flow rate (MFR). Body and cardiac weights, plasma levels of brain naturetic peptide (BNP), cardiac troponin I (cTnI), vitamin D and total calcium and cardiac tissue heat shock protein 20, total antioxidant capacity (TAC) and malondialdehyde (MDA) were measured. Also, cardiac tissues were histopathologically assessed. Results: Dox-treated rats showed significant decrease in the final body weight (fBW), significant prolongation of the P-R interval, QRS duration, observed Q-T (Q-TO) and corrected Q-T (Q-Tc) with significant depression of the R voltage. In addition, there was a significant decrease in the in vitro heart rate, significant depression in PT, PT/LV and MFR together with significant prolongation in TPT& 3 HRT. These changes were accompanied by significant elevation of plasma BNP, cTnI and in cardiac tissue MDA and a significant decrease in plasma vit D, total calcium and cardiac tissue TAC and HSP20. Histopathological examination revealed markedly distorted muscle fibers with indistinct cell borders, bright eosinophilic cytoplasm, intra-cytoplasmic vacuoles and small pyknotic nuclei or absent nuclei, together with interstitial edema & aggregates of inflammatory cells and thick irregular collagen fibers in between the muscle fibers. Concomitant supplementation of vitamin D to the doxorubicin treated rats resulted in significant decrease in PR interval, QRS duration, MDA and significant increase PT, PT/LV, MFR, MFR/LV, plasma vitamin D, total calcium and TAC compared to the Dox treated rats to be insignificantly different from the control group. Plasma BNP and cTnI were significantly decreased while cardiac HSP20 was significantly increased compared to the Dox-treated rats, yet these parameters were still significant from the control group. Meanwhile, fBW, Q-TO and Q-Tc intervals, and TPT remained insignificantly changed from the DOX group. These findings were associated by regaining the normal collagen fiber distribution between cardiac muscle fibers with resolution of interstitial edema. Conclusion: Vitamin D supplementation can partially mitigate cardiac dysfunction induced by chronic doxorubicin by improving the cardiac antioxidant state and heat shock protein 20 level. Key words: Doxorubicin, cardiac dysfunction, vitamin D, isolated heart studies, BNP, HSP20.
Obesity is one of the most prevalent public health issues. Excess weight has been associated with autonomic dysfunction, but the evidence in young adults is scarce. Therefore, this study aims to assess the relationship between the body mass index (BMI) and the autonomic nervous system (ANS) function in young adults. Males are known to have higher sympathetic nervous system activity as compared to females, who are known to have a greater parasympathetic function. Hence, it is critical to assess the differences in ANS activity based on gender. This study was done on 120 university students aged 18 - 25 years, categorized based on BMI as normal (18kg/m2-24kg/m2) and obese (>25kg/m2). The ANS function was assessed by performing the Isometric Handgrip Test (IHGT), Deep Breathing Test (DBT), and Cold Pressor Test (CPT). Our study revealed that obese individuals exhibited an increase in the blood pressure and heart rate as compared to normal individuals, indicating that the former might be at greater risk for the development of ANS dysfunction. Our study also revealed that obese males exhibited a greater change in their blood pressure as compared to their obese counterparts.
Background: Re-perfusion strategies are the current standard therapy for acute myocardial infarction, despite the spectrum of re-perfusionassociated pathologies that may contribute to irreversible myocardial injury.
Objectives Re-perfusion is the standard therapy for acute myocardial infarction, despite the associated pathologies that may contribute to irreversible myocardial injury. The present study aims to clarify the alterations in cardiac activities in response to experimental cardiac ischemic arrest followed by re-perfusion in isolated hearts perfused with nitric oxide (NO) donor, l-arginine, or NO inhibitor, Nω-Nitro-l-arginine methyl ester hydrochloride (l-NAME), to shed light on the possible role of NO in the re-perfusion process. Methods Hearts isolated from adult Wistar rats were studied on Langendorff preparation under basal conditions and during 30 min re-perfusion following 30 min of total global ischemia. Rats were randomly divided into three groups; control and l-arginine or l-NAME infused heart groups. Cardiac tissue content of malondialdhyde, catalase and nitrite was also measured. Results Compared to the control group, both l-arginine and l-NAME infused hearts showed increased basal chronotropy and myocardial flow rate. Following ischemia and during the whole period of re-perfusion, the three groups demonstrated significant deterioration in the inotropic activity and compromised myocardial flow rate. l-arginine infused hearts revealed depressed inotropy and chronotropy, weak systolic and diastolic functions with compromised myocardial flow at early 5 min of re-perfusion, yet with significantly higher myocardial flow rate by the end of re-perfusion. Conclusions Reducing NO availability by l-NAME revealed mild impact on the ischemia re-perfusion induced contractile dysfunction, whereas excess NO worsens cardiac performance at the early re-perfusion period.
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