Calcium current kinetics in young and aged human cultured myotubes.
There is evidence that the complex process of sarcopenia in human aged skeletal muscle is linked to the modification of mechanisms controlling Ca(2+) homeostasis. To further clarify this issue, we assessed the changes in the kinetics of activation and inactivation of T- and L-type Ca(2+) currents in in vitro differentiated human myotubes, derived from satellite cells of healthy donors aged 2, 12, 76 and 86 years. The results showed an age-related decrease in the occurrence of T- and L-type currents. Moreover, significant age-dependent alterations were found in L-(but not T) type current density, and activation and inactivation kinetics, although an interesting alteration in the kinetics of T-current inactivation was observed. The T- and L-type Ca(2+) currents play a crucial role in regulating Ca(2+) entry during satellite cells differentiation and fusion into myotubes. Also, the L-type Ca(2+) channels underlie the skeletal muscle excitation-contraction coupling mechanism. Thus, our results support the hypothesis that the aging process could negatively affect the Ca(2+) homeostasis of these cells, by altering Ca(2+) entry through T- and L-type Ca(2+) channels, thereby putting a strain on the ability of human satellite cells to regenerate skeletal muscle in elderly people.
Luin
Elisa
E
Department of Physiology and Pathology, University of Trieste, Via A. Fleming 22, I-34127 Trieste, Italy. elisaluin@dfp.units.it
Lorenzon
Paola
P
Wernig
Anton
A
Ruzzier
Fabio
F
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000378:metabolism; D020013:Calcium Signaling; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D006801:Humans; D015640:Ion Channel Gating; D007700:Kinetics; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism*
D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type