AMPK Methods and Protocols

An important observation in this regard was the apparent asso-

ciation of age with AMPK activity, peaking early on (~2 weeks) but

subsequently falling below TGWTlevels (after ~4 weeks). This,

coupled with the finding that reduction in AMPK activity extended

to involveγ1-containing AMPK complexes in older mice, high-

lighted the critical role of an extrinsic factor in modulating the

primary effect of mutations inγ2[ 34]. The inverse correlation

between myocardial glycogen levels (which steadily accumulate

with age) and AMPK activity in TG mice overexpressing mutant

PRKAG2provided a clear substrate for this (Fig.6)[ 35]. Substan-

tiating the primary impact ofγ2-mutations on the holoenzyme,

200

A

B

C

150

100

100

2 Days

*

*

2 Days

Age (weeks)^1

WT TG WT TG WT TG WT TG WT TG

24 820

P-AMPK

Loading control

1 Week

1 Week

2 Weeks

2 Weeks

Age

Age

Glycogen Content(Fold Over Control)

AMPK Activity (% of Control)

4 Weeks

4 Weeks

8 Weeks

8 Weeks

12 Weeks 20 Weeks

WT

TG T400N

WT

TG T400N

20 Weeks

80

60

40

20

0

50

0

Fig. 6Inverse association between myocardial AMPK activity and glycogen content in TGT400Nmice. Temporal
change in cardiac AMPK activity (a), glycogen content (b), and panα-Thr172 phosphorylation (P-AMPK) (c)in
TGT400Nmice (Reproduced from ref.35 with permission from Elsevier)

598 Arash Yavari et al.