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Skeletal Muscle
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
In practically all body cells, the main source of ATP is the citric acid cycle, also known as the tricarboxylic acid cycle or the Krebs cycle, which can metabolize all forms of nutrients, that is, carbohydrates, fats, and proteins. The input to the cycle is from glycolysis, and the output feeds oxidative phosphorylation, which provides most of the ATP, using oxygen, ADP, and phosphate (Figure 9.7). Both the citric acid cycle and oxidative phosphorylation occur in the mitochondria. Glycolysis is the metabolic pathway that breaks down one glucose molecule into two pyruvate molecules, the ionized form of pyruvic acid, and occurs in the cytoplasm outside the mitochondria. Under aerobic conditions, that is in the presence of oxygen, pyruvate feeds into the citric acid cycle, but under anaerobic conditions, that is in the absence of oxygen, pyruvate is converted to lactate.
Interdependence Between Cardiac Function, Oxygen Demand, and Supply
Published in Samuel Sideman, Rafael Beyar, Analysis and Simulation of the Cardiac System — Ischemia, 2020
Joseph S. Janicki, Karl T. Weber, Ponnambalam Sundram
The capacity of the heart for work is almost entirely dependent on aerobic conditions. As illustrated in Figure 1, the amount of O2 available to the myocardium is determined by: Arterial O2 content and hemoglobin concentrationCoronary flow and its distribution within the myocardiumThe anatomic characteristics of the coronary microcirculation, including the relation of capillaries to muscle fibers and the diffusion distance for O2The ability of the myocardium to extract O2
Metabolism
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The end product of glycolysis is pyruvate, which under aerobic conditions enters the citric acid cycle. Under aerobic conditions, the NADH + H+ formed by reaction ⑥ in Figure 65.3 is transferred indirectly to the mitochondrial electron transport chain to produce more ATP. This NADH + H+ from glycolysis in the cytoplasm is a charged molecule and cannot pass through the mitochondrial wall, but the electrons from the molecule can be transferred to any available NAD+ or FAD inside the mitochondria. (Under aerobic conditions, glycolysis can therefore continue, as NAD+ used up in reaction ⑥ is regenerated by this process.) Under anaerobic conditions, glycolysis can still continue, as two electrons can be transferred from NADH + H+ to pyruvate (to form lactate) to regenerate NAD+ and maintain reaction ⑥, although the process is less efficient in producing ATP than under aerobic conditions, and lactate is accumulated in the cell.
Protective effect and mechanism of low P50 haemoglobin oxygen carrier on isolated rat heart
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2022
Wentao Zhou, Shen Li, Shasha Hao, Honghui Zhang, Tao Li, Wanjing Li, Jiaxin Liu, Hong Wang, Chengmin Yang
Low P50 HBOCs have better protective effect on cardiac function, the indexes in this study to evaluate cardiac function included LVDevP, LVEDP, ±dp/dt and HR. The results suggest that the recovery of ± dp/dt in the HBOCs groups was better than that of the control group (p < .05), the recovery of ± dp/dt in low P50 HBOCs group was better than that of the medium and high P50 HBOCs groups (p < .05). The possible reason is that the heart is an organ that consumes a lot of oxygen, the ischaemic area should be capillaries firstly, the high P50 HBOCs can provide sufficient oxygen to the large blood vessels in time, but it can’t be maintained oxygen during transportation to the capillaries. Aerobic conditions, because this study belonging to a model study of an isolated heart cannot be supplemented with oxygen in the body’s circulation, it is necessary to convert all haemoglobin to oxyhaemoglobin before perfusion in order to play a role of oxygen supply in the isolated heart. The role of oxygen supplementation is particularly important for the balanced release of oxygen in large blood vessels and capillaries [15,16]. So, the control group can’t provide oxygen, hypoxic tissues and organs cannot get oxygen supply in time, causing damage to cells and the body, and the high P50 HBOCs can provide sufficient oxygen to the large blood vessels in time, but it can’t be maintained oxygen during transportation to the capillaries, low P50 HBOCs can release oxygen in large blood vessels and appropriate amount of oxygen in capillaries. Therefore, it can effectively protect myocardial cells and optimize the cardiac function.
Cadmium exposure induces cardiac glucometabolic dysregulation and lipid accumulation independent of pyruvate dehydrogenase activity
Published in Annals of Medicine, 2021
Olufemi I. Oluranti, Ebunoluwa A. Agboola, Nteimam E. Fubara, Mercy O. Ajayi, Olugbenga S. Michael
For continuous contraction to propel blood throughout the body, the heart needs a constant and significant energy supply and, thus, has established an elaborate metabolic system for the use of all carbon substrates. It relies mainly on the fatty acid oxidation (∼60–90%) and to a lesser degree on glucose (∼10–40%), ketone bodies, lactate for its energy output [1]. However, the myocardial metabolic mechanism is extremely versatile, allowing a range of physiological and pathological conditions to alter the choice of the substrate. While it is thought that a cardiac metabolic transition is an adaptive response to the availability of cardiac substrate. Evidence supports the belief that the preference for myocardial substrate changes may play a causal role in cardiac dysfunction [2,3]. The heart's energy supply is met by the combined use of various substrates. Nevertheless, glucose and fatty acids constitute the main energy sources under aerobic conditions, with fatty acids contributing a greater part of this energy supply [4–6]. Lipoproteins are the primary sources of cardiac tissue fatty acids, and lipoprotein lipase (LPL) is the rate-limiting triglyceride hydrolysis found in these molecules [7]. Disorders in the metabolism and energy of cardiac substrates have been reported to be the major contributors to cardiac dysfunction like diabetic cardiomyopathy (DCM) [8,9].
Low prevalence of multi-resistant bacteria in undergraduate dental students; an observational case-control multi-centre study in Europe
Published in Journal of Oral Microbiology, 2021
C.M.C. Volgenant, M.A. Hoogenkamp, G. Dahlén, S. Kalfas, S. Petti, J.J. De Soet
Each participant received a questionnaire to collect demographic data. Questions on antibiotic use, hospital visits, patient treatment status and living in the vicinity of a livestock were asked to assess possible cofounders. After completion of the survey form, the students were carefully instructed on how to take the clinical sample. Three sites, each with a separate sterile cotton swab (Sarstedt, Nümbrecht, Germany), were sampled: (1) the interdigital folds between the ring- and little-finger on their dominant hand, (2) both anterior nares of their nose and (3) the dorsum of their tongue. Samples were immediately transported to a microbiology laboratory, and cultured in 500 µl Tryptic Soy Broth (TSB, BD, Sparks Glencoe, MD, USA). Cultures were stored at −80°C and stored until further analyses after the addition of 500 µl 60% (v/v) glycerol (Merck, Darmstadt, Germany). All culturing on solid media and in TSB were performed under aerobic conditions at 37°C for either 24 or 16 hours, respectively.