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X-Nuclei MRI and Energy Metabolism
Published in Guillaume Madelin, X-Nuclei Magnetic Resonance Imaging, 2022
ATP hydrolysis. ATP hydrolysis is the catabolic (exergonic) reaction process by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in ATP is released by splitting these bonds, and which results in products ADP and Pi. ADP can even be further hydrolyzed to release more energy, and products adenosine monophosphate (AMP), and another Pi. ATP is hydrolyzed in the following reaction: ATP+H2O⇌ADP+Pi+energy
Elements of Bioelectricity
Published in Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu, Interdisciplinary Engineering Sciences, 2020
Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu
The energy, which is provided for the transport, is provided by ATP hydrolysis as well as thermodynamic free energy of various ions and solutes which is available in their concentration gradient. The ATP hydrolysis is utilized by pumps via primary active transport. In the secondary active transport, thermodynamic free energy available in the concentration gradient of solutes and ions is utilized for the transport by cotransporters and exchangers. Pumps, which utilize the energy provided by ATP hydrolysis, are called as ATPases. Most prominent ATPase is the Na–K pump, which extrudes three Na+ ions from a cell with a concurrent uptake of two K+ ions into the cell for hydrolysis of one molecule of ATP. This pump is generally called as electrogenic, because there is a net transfer of charge across the membrane. The Na–K pump is the only membrane protein that transfers Na+ ions through primary active transport.1,2,4
Mechanism of linear motors
Published in Peixuan Guo, Zhengyi Zhao, Biomotors: Linear, Rotation, and Revolution Motion Mechanisms, 2017
Linear motors are characterized by their ability to move or generate force through interaction with a specific cellular track (cytoskeletal filaments, DNA, or RNA). The motion of many of these motors has been described as “walking,” where they advance one foot—or head, in this case—at a time. Two cytoskeletal motors, myosin and kinesin, are members of the P-loop NTPases that share structural homology in the nucleotide binding region (Kull et al., 1998). Dynein is a more complex motor that has six ATP binding regions and is a member of the AAA+ ATPase family (Roberts et al., 2013). To highlight the features of linear motors, in this section we will focus on the myosin superfamily, consisting of around 2000 motors divided into 35 classes that are ubiquitously expressed in eukaryotic cells (Odronitz & Kollmar, 2007). Myosins are capable of interacting cyclically, with actin filaments utilizing the chemical energy derived from ATP hydrolysis to perform mechanical work (Sellers & Goodson, 1995). By virtue of this mechanical work, these motors can translocate actin filaments or act as tethers/anchors to generate tension and force. Moreover, certain classes of myosin motors can also act as point-to-point transporters, thus individually moving cargo on actin filaments.
Mathematical modeling of the cardiac tissue
Published in Mechanics of Advanced Materials and Structures, 2022
A number of models of the chemical kinetics of muscle contraction are known from the literature (see Reviews in Long [87], Long and McIntire [88, 89], Huxley [99], Zozulya et al. [43], etc.). In all models, the fundamental features of muscle biochemistry are clearly presented. The energy supplier for mechanical muscle contraction is ATP hydrolysis. Under aerobic and anaerobic conditions in the muscular system, exchange occurs only between Ca2+, ions, actomyosin and total phosphate. The concentration of ATP remains almost constant under normal physiological conditions of muscle function. In addition, on the basis of known physiological facts and chemical simplifications, a number of assumptions are introduced that do not affect the quality of modeling. It is assumed that no attractive diffusion mechanism is required to bring energy to a point; chemical energy is stored in any elementary volume of tissue. This hypothesis of continualization is traditionally used in rigid body mechanics, and in this case it has a physiological interpretation. When oxygen is not available, muscles act by anaerobic glycolysis. When glycolysis is blocked, functioning occurs due to the transphosphate transition of phosphocreatine to ATP.
Glucosamine modulates membrane and cellular ionic homeostasis: studies on accelerated senescent and naturally aged rats
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Komal Saraswat, Raushan Kumar, Syed Ibrahim Rizvi
The mammalian erythrocyte membrane provides a valuable model to investigate aging-related changes [6,7]. Erythrocyte membrane-bound transporters or pumps such as Ca2+ATPase (PMCA pump), Na+/K+-ATPase (NKA pump), and Na+/H+ exchanger (NHE) use the energy of ATP hydrolysis to move ions or small molecules across the membrane against a chemical concentration gradient or electric potential [8]. A close relationship has been established between the impairment in the activities of various membrane transporters and the development of pathologies [9].