ME. Circadian rhythms in myocardial metabolism and contractile function: influence of workload and oleate. Am J Physiol Heart Circ Physiol 293: H2385-H2393, 2007. First published July 6, 2007; doi:10.1152/ajpheart.01361.2006.-Multiple extracardiac stimuli, such as workload and circulating nutrients (e.g., fatty acids), known to influence myocardial metabolism and contractile function exhibit marked circadian rhythms. The aim of the present study was to investigate whether the rat heart exhibits circadian rhythms in its responsiveness to changes in workload and/or fatty acid (oleate) availability. Thus, hearts were isolated from male Wistar rats (housed during a 12:12-h light-dark cycle: lights on at 9 AM) at 9 AM, 3 PM, 9 PM, and 3 AM and perfused in the working mode ex vivo with 5 mM glucose plus either 0.4 or 0.8 mM oleate. Following 20-min perfusion at normal workload (i.e., 100 cm H 2O afterload), hearts were challenged with increased workload (140 cm H 2O afterload plus 1 M epinephrine). In the presence of 0.4 mM oleate, myocardial metabolism exhibited a marked circadian rhythm, with decreased rates of glucose oxidation, increased rates of lactate release, decreased glycogenolysis capacity, and increased channeling of oleate into nonoxidative pathways during the light phase. Rat hearts also exhibited a modest circadian rhythm in responsiveness to the workload challenge when perfused in the presence of 0.4 mM oleate, with increased myocardial oxygen consumption at the dark-to-light phase transition. However, rat hearts perfused in the presence of 0.8 mM oleate exhibited a markedly blunted contractile function response to the workload challenge during the light phase. In conclusion, these studies expose marked circadian rhythmicities in myocardial oxidative and nonoxidative metabolism as well as responsiveness of the rat heart to changes in workload and fatty acid availability. fatty acids; glucose; glycogen; triglyceride CIRCADIAN RHYTHMS IN CARDIOVASCULAR PHYSIOLOGY and pathophysiology are well established. Heart rate, blood pressure, cardiac output, platelet aggregability, myocardial infarction, arrhythmias, and sudden cardiac death all exhibit marked circadian rhythmicities in both humans and animal models (3,7,12,18,23,33). To date, these observations have been attributed primarily to diurnal variations in multiple extracellular stimuli (i.e., neurohumoral factors) such as autonomic and sympathetic activity (23,24,32). However, it is becoming increasingly clear that the intrinsic properties of cardiovascular components change over the course of the day, suggesting that oscillations in responsiveness to extracellular stimuli may contribute toward circadian rhythmicities in cardiovascular events (36, 37).Myocardial metabolism and contractile function are inextricably interlinked. For example, increased energy demand during periods of elevated workload is balanced by increased oxidative and nonoxidative metabolism (17). An inability of the heart to maintain adequate ATP supply will in turn adversely affect...
Aim: This present study was carried out to ascertain the influences of ABO and Rhesus blood groups on blood pressure and hypertension among normotensive and hypertensive patients attending cardiologic clinic in Niger delta University Teaching Hospital, Okolobiri in Yenagoa Local Government Area of Bayelsa State Nigeria. Study Design: Cross sectional study design was adopted. Place and Duration of Study: The study was carried out in the Cardiology Clinics in the Niger Delta University Teaching Hospital (NDUTH), Okolobiri, Bayelsa State, from February 2020 to November 2020. Methodology: This study was carried out on 800 participants, consisting of 400 each of apparently healthy Normotensive and Hypertensive individuals. The blood pressures were determined using palpatory and auscultatory (stethoscope and sphygmomanometer) method in both control and hypertensive groups and their ABO and Rhesus blood groups were determined using the slide haemagglutination technique. Statistical analysis was done using SPSS statistical software to perform Chi-square test. Results: The frequency of the various blood groups was A-20.0%, B-16.8%, AB-13.3% and O-50.0% for the normotensive individuals and A-12.0%, B-15.5%, AB-17.8% and O-54.8%, for the hypertensive individuals. The frequency of ABO blood groups in both the normotensive and hypertensive group was therefore found to be O>B>A>AB. The prevalence of blood group O and rhesus O-ve was found to be associated with elevated blood pressure and the development of hypertension while prevalence of blood group AB was found to be lowest in the same group, but was not significant statistically (p>0.05). There was no significant difference between systolic and diastolic blood pressure of different blood groups. Conclusion: Blood group O was found to be the most common blood group in our study. Blood group O- was also found to be more prone to hypertension. However, there was no statistically significant association between ABO blood groups and Hypertension.
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