Cp. Ingalls et al., Time course changes in [Ca2+](i), force, and protein content in hindlimb-suspended mouse soleus muscles, AVIAT SP EN, 72(5), 2001, pp. 471-476
Citations number
30
Categorie Soggetti
Envirnomentale Medicine & Public Health","Medical Research General Topics
Background: Exposure to reduced gravitational forces during spaceflight is
associated with significant reductions in skeletal muscle mass and strength
. The purpose of this study was to test the hypothesis that increases in re
sting cytosolic free calcium concentration ([Ca2+](i)) would precede reduct
ions in protein content and maximal isometric tetanic force (Po) in mouse s
oleus muscle after initiation of hindlimb suspension. Methods: Female ICR m
ice (n = 42) were hindlimb suspended for 1, 2, 3, 5, or 7 d; weight-matched
mice were used as controls. Following the hindlimb suspension, the left so
leus muscle was used to determine Po in vitro and the right soleus muscle w
as used to determine protein content and [Ca2+](i) via confocal laser scann
ing microscopy. Results: Compared with controls, [Ca2+](i) was elevated by
38% at 2 d, and 117% at 7 d. Compared with controls, soleus muscle total an
d myofibrillar protein contents were reduced 27-29% and 30-34%, respectivel
y, at 5-7 d after initiation of hindlimb suspension. Compared with controls
, soleus muscle Po was decreased by 24% at 3 d, and 38% at 7 d. Conclusion:
It appears that resting cytosolic Ca2+ homeostasis is disturbed soon after
the initiation of hindlimb suspension, and these elevations in ICa2+]i may
play a role in initiating soleus muscle atrophy.