Growth hormone reverses age-related cardiac myofilament dysfunction in rats.
We tested the hypotheses that aging is associated with a reduction in overall cardiac contractility and myofilament force generation that could be reversed with growth hormone (GH) replacement. Three groups of male Brown-Norway rats were studied: young (Y(SAL): 8 mo old, n = 13), old (O(SAL): 28 mo old, n = 13), and old GH-treated (O(GH): 28 mo old, n = 12; 300 microg bovine GH, twice a day for 30 days). The left ventricular (LV) pressure-volume relation was derived in isolated hearts, after which isolated trabecular muscles from these hearts were permeabilized and maximal myofilament force generation (Fmax) was measured. LV developed pressures at a LV volume of 0.3 ml were significantly depressed with age: 84 +/- 6 vs. 71 +/- 6 mmHg (Y(SAL) vs. O(SAL), respectively, P = 0.001) and not restored by GH (69 +/- 4 mmHg). Fmax was reduced in the aged hearts: 47.5 +/- 3.12 vs. 35.9 +/- 3.03 mN/mm2 (Y(SAL) vs. O(SAL), respectively, P = 0.014) but was restored with GH replacement to 46.7 +/- 3.12 mN/mm2 (O(SAL) vs. O(GH), P = 0.021). Our results suggest that cellular myofilament contractility is reduced with aging and restored with GH replacement.
Wannenburg
T
T
Department of Cardiology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1083, USA. teannen@wfubmc.edu
Khan
A S
AS
Sane
D C
DC
Willingham
M C
MC
Faucette
T
T
Sonntag
W E
WE
D000375:Aging / Q000473:pathology* / Q000502:physiology*; D000818:Animals; D013006:Growth Hormone / Q000494:pharmacology*; D006321:Heart / Q000502:physiology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology; D009206:Myocardium / Q000473:pathology*; D051381:Rats; D011914:Rats, Inbred BN
D013006:Growth Hormone