Amino muscle physiology

This results in the extrusion of three positive charges for every two that enter the cell, resulting in a transmembrane potential of 50-70 mV, and has enormous physiological significance. More than one-third of the ATP utilized by resting mammalian cells is used to maintain the intracellular Na+-K+ gradient (in nerve cells this can rise up to 70%), which controls cell volume, allows neurons and muscle cells to be electrically excitable, and also drives the active transport of sugars and amino acids (see later). 

Liver, small intestine, muscle and kidney all participate in amino acid catabolism with the liver, under most conditions, playing the major role, but the metabolism of specific amino acids in the other three tissues is of considerable biochemical and physiological importance (see below). 

Structure-activity data on the effects of flatworm FaRPs on 5. mansoni muscle fibres reveal that the replacement of any residue in the YIRFamide signature with the amino acid alanine abolished peptide activity (Day et al., 1997). Although no trematode FaRP has been structurally characterized, evidence from physiology studies reveals that the YIRFamide-containing peptides induce contraction of dispersed 5. mansoni muscle fibres with high... 

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