The intracellular concentration of free magnesium in extensor digitorum longus muscles of the rat

Abstract

SUMMARYMagnesium-sensitive microelectrodes were used to measure the intracellular concentration of free Mg2+, [Mg2+]f, in rat extensor digitorum longus muscles in vitro at 30 'C. The intracellular activities of Na+ and K+ were also determined so that allowance could be made for the interference from these ions with the Mg2+ electrode response. The mean value for [Mg2+], based on twenty-six measurements in twelve muscles was 0-47 mM.

The Influence of Streptozotocin Diabetes and Metformin on Erythrocyte Volume and on the Membrane Potential and the Contractile Characteristics of the Extensor Digitorum Longus and Soleus Muscles in Rats

“…The distal tendon of the EDL or soleus muscle was attached to a strain guage transducer (Piodon Controls Ltd, unloaded resonant frequency of 600 Hz) which was mounted on a micropositioner. Krebs solution (MacDermott, 1990) at 37°C was circulated over the exposed muscle. This served to keep the muscle moist and warm.…”

Sites of Superoxide and Hydrogen Peroxide Production by Muscle Mitochondria Assessed ex Vivo under Conditions Mimicking Rest and Exercise

“…Targeted free Mg 2ϩ concentrations were 600 M (rest), 600 M (mild aerobic exercise), and 1000 M (intense aerobic exercise) (40,(87)(88)(89). Targeted Na ϩ concentrations were 16 mM for all media (65,89). Media had K ϩ and Cl Ϫ adjusted to give an osmolarity of 290 mosM (90 -92).…”

“…Published values were corrected for plasma concentrations where appropriate and for the distribution of intracellular metabolites between cytosol and mitochondria, using the following matrix/cytosol ratios from heart and liver (or the assumed values for metabolites in parentheses): glycerol 3-phosphate, glutamine (dihydroxyacetone phosphate, taurine): 0 (68,69) (83)(84)(85)(86). Targeted free Mg 2ϩ concentrations were 600 M (rest), 600 M (mild aerobic exercise), and 1000 M (intense aerobic exercise) (40,(87)(88)(89). Targeted Na ϩ concentrations were 16 mM for all media (65,89).…”

Factors influencing the inhibition of protein kinases

“…β and K I were calculated from measurements of K I app realized at two independent peptide concentrations. ] f ) found in living cells is in the low millimolar range and close to 0.5 mM 21,22 . We therefore decided to measure the kinetic parameters of phosphorylated IGF1R at low (0.5 mM) and high (10 mM) [Mg 2+ ] f (Figure 1).…”