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The Cell Membrane in the Steady State
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
A uniporter is a transmembrane protein that facilitates diffusion of a substance down a concentration gradient, without ATP hydrolysis, but at a rate that can be far higher than that of passive diffusion for that substance, the energy being derived from the concentration gradient of the transported substance. Glucose and amino acids are transported across the plasma membrane in this manner, the concentration gradient being established in these cases because these substances are used up in cell metabolism. The inner mitochondrial membrane has an efficient Ca2+ uniporter that allows a fast uptake of Ca2+ by mitochondria. This type of movement is referred to sometimes as facilitated transport, or facilitated diffusion. In a uniporter, a specific protein transports a particular substance by undergoing a conformational change, much like that illustrated in Figure 2.5 for the Na+-K+ pump but without ATP hydrolysis.
Physical properties of the body fluids and the cell membrane
Published in Ronald L. Fournier, Basic Transport Phenomena in Biomedical Engineering, 2017
Figure 3.7 illustrates the passive transport of solutes through the cell membrane by either carrier proteins or channel proteins. Carrier proteins can transport only a single solute across the membrane, a process called uniport, or there can be transport of two different solutes, called coupled transport. The passive transport of glucose into a cell by glucose transporters is an example of a uniport. In coupled transport, the transfer of one solute occurs in combination with the transport of another solute. This coupled transport of the two solutes can occur with both solutes transported in the same direction, symport, or in opposite directions, antiport. An example of coupled transport is the sodium ion gradient–driven symport of glucose and sodium ions.
Serum from differently exercised subjects induces myogenic differentiation in LHCN-M2 human myoblasts
Published in Journal of Sports Sciences, 2018
D. Vitucci, E. Imperlini, R. Arcone, A. Alfieri, A. Canciello, L. Russomando, D. Martone, A. Cola, G. Labruna, S. Orrù, D. Tafuri, A. Mancini, P. Buono
In this study we also examined the effects of human serum factors, such as IGF-1, on myogenic differentiation. We found that serum from differently exercised subjects, containing high levels of IGF-1, induces myogenic differentiation in LHCN-M2 cells, differently from untrained subject’s serum, containing low IGF-1 levels. This finding prompts us to speculate that IGF-1 plays a crucial role in the myogenic differentiation process in LHCN-M2 cells. A series of previously reported results are consistent with this concept. In particular, it has been demonstrated that IGF-1, together with myogenic regulatory factors, is involved in the progression of satellite cell activation during myogenesis and muscle regeneration (Shi & Garry, 2006; Zanou & Gailly, 2013). More recently, it was found that blood factors mediate tissue adaptation in response to exercise in sedentary rats (Goutianos et al., 2016). Notably, serum from exercised subjects was found to affect mitochondrial calcium uniporter expression levels, which in turn conteracts age-related muscle loss in sarcopenia and also reduces the oxidative stress that cause many different dysmetabolic and cardiovascular diseases (Conti et al., 2012; Zampieri et al., 2016). Furthermore, other studies demonstrated that circulating blood factors favour synaptic plasticity in the brain of elderly mice, and reduce age-related cardiac hypertrophy (Loffredo et al., 2013; Villeda et al., 2014).