ANG II is required for optimal overload-induced skeletal muscle hypertrophy.
ANG II mediates the hypertrophic response of overloaded cardiac muscle, likely via the ANG II type 1 (AT(1)) receptor. To examine the potential role of ANG II in overload-induced skeletal muscle hypertrophy, plantaris and/or soleus muscle overload was produced in female Sprague-Dawley rats (225-250 g) by the bilateral surgical ablation of either the synergistic gastrocnemius muscle (experiment 1) or both the gastrocnemius and plantaris muscles (experiment 2). In experiment 1 (n = 10/group), inhibiting endogenous ANG II production by oral administration of an angiotensin-converting enzyme (ACE) inhibitor during a 28-day overloading protocol attenuated plantaris and soleus muscle hypertrophy by 57 and 96%, respectively (as measured by total muscle protein content). ACE inhibition had no effect on nonoverloaded (sham-operated) muscles. With the use of new animals (experiment 2; n = 8/group), locally perfusing overloaded soleus muscles with exogenous ANG II (via osmotic pump) rescued the lost hypertrophic response in ACE-inhibited animals by 71%. Furthermore, orally administering an AT(1) receptor antagonist instead of an ACE inhibitor produced a 48% attenuation of overload-induced hypertrophy that could not be rescued by ANG II perfusion. Thus ANG II may be necessary for optimal overload-induced skeletal muscle hypertrophy, acting at least in part via an AT(1) receptor-dependent pathway.
Gordon
S E
SE
Department of Integrative Biology and Pharmacology, University of Texas--Houston Health Science Center, Houston, Texas 77030, USA.
Davis
B S
BS
Carlson
C J
CJ
Booth
F W
FW
D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D001284:Atrophy; D004326:Drinking; D004435:Eating; D005260:Female; D006984:Hypertrophy; D009124:Muscle Proteins / Q000032:analysis; D018482:Muscle, Skeletal / Q000737:chemistry / Q000473:pathology* / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000378:metabolism; D013314:Stress, Mechanical; D014662:Vasoconstrictor Agents / Q000378:metabolism* / Q000494:pharmacology; D016474:Weight-Bearing / Q000502:physiology
D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D009124:Muscle Proteins; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D014662:Vasoconstrictor Agents; D000804:Angiotensin II