Intracellular calcium movements in skinned muscle fibres

J Physiol. 1972 May;223(1):21-33. doi: 10.1113/jphysiol.1972.sp009831.


1. Force development and (45)Ca movement between the internal membranes and the myofilament space were measured in segments of skinned muscle fibres.2. At 20 degrees C calcium ions in the myofilament space of calcium loaded fibres caused the internal membranes to release a substantial amount of calcium which produced a large force spike. Calcium produced a similar force spike in fibres containing only the physiological level of calcium when the temperature was lowered to about 6 degrees C.3. The force spike at 6 degrees C was inhibited when the magnesium concentration in the bathing solution was increased from 1 to 6 mM. The pattern of force development in preparations transferred directly from oil to a free calcium solution indicated that the normal concentration of Mg(2+) in the myofilament space of intact fibres is of the order of 10(-3)M.4. A possible role for the regenerative calcium release mechanism in the physiological activation of muscle fibres is suggested.

MeSH terms

  • Action Potentials
  • Animals
  • Anura
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Calcium Isotopes
  • In Vitro Techniques
  • Magnesium / metabolism
  • Magnesium / pharmacology
  • Membranes / metabolism
  • Muscle Contraction / drug effects
  • Myofibrils / metabolism*
  • Sarcoplasmic Reticulum / metabolism
  • Temperature


  • Calcium Isotopes
  • Magnesium
  • Calcium