Slowing of relaxation of (Ca-2+) -i during prolonged tetanic stimulation of single fibres from Xenopus skeletal muscle
Westerblad, H.; Allen, D., G.
Journal of Physiology (Cambridge) 492(3): 723-736
Parvalbumin (PA) has been proposed to take up Ca-2+ and enhance skeletal muscle relaxation in brief contractions; as the duration of the contraction is increased, PA will become saturated with Ca-2+ and no longer contribute to relaxation which therefore will be slowed. The rate of Ca-2+ loading of PA is determined by the Mg-2+ off rate (about 4 s-1 at 22 degree C).