Back to Search
Start Over
AT1 receptor participates in the cardiac hypertrophy induced by resistance training in rats
- Source :
- American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 295:R381-R387
- Publication Year :
- 2008
- Publisher :
- American Physiological Society, 2008.
-
Abstract
- Resistance training is accompanied by cardiac hypertrophy, but the role of the renin-angiotensin system (RAS) in this response is elusive. We evaluated this question in 36 male Wistar rats divided into six groups: control ( n = 6); trained ( n = 6); control + losartan (10 mg·kg−1·day−1, n = 6); trained + losartan ( n = 6); control + high-salt diet (1%, n = 6); and trained + high-salt diet (1%, n = 6). High salt was used to inhibit the systemic RAS and losartan to block the AT1 receptor. The exercise protocol consisted of: 4 × 12 bouts, 5×/wk during 8 wk, with 65–75% of one repetition maximum. Left ventricle weight-to-body weight ratio increased only in trained and trained + high-salt diet groups (8.5% and 10.6%, P < 0.05) compared with control. Also, none of the pathological cardiac hypertrophy markers, atrial natriuretic peptide, and αMHC (α-myosin heavy chain)-to-βMHC ratio, were changed. ACE activity was analyzed by fluorometric assay (systemic and cardiac) and plasma renin activity (PRA) by RIA and remained unchanged upon resistance training, whereas PRA decreased significantly with the high-salt diet. Interestingly, using Western blot analysis and RT-PRC, no changes were observed in cardiac AT2 receptor levels, whereas the AT1 receptor gene (56%, P < 0.05) and protein (31%, P < 0.05) expressions were upregulated in the trained group. Also, cardiac ANG II concentration evaluated by ELISA remained unchanged (23.27 ± 2.4 vs. 22.01 ± 0.8 pg/mg, P > 0.05). Administration of a subhypotensive dose of losartan prevented left ventricle hypertrophy in response to the resistance training. Altogether, we provide evidence that resistance training-induced cardiac hypertrophy is accompanied by induction of AT1 receptor expression with no changes in cardiac ANG II, which suggests a local activation of the RAS consistent with the hypertrophic response.
- Subjects :
- Male
medicine.medical_specialty
Physiology
Blotting, Western
Physical Exertion
Hemodynamics
Enzyme-Linked Immunosorbent Assay
Physical exercise
Polymerase Chain Reaction
Receptor, Angiotensin, Type 2
Losartan
Receptor, Angiotensin, Type 1
Muscle hypertrophy
Renin-Angiotensin System
Downregulation and upregulation
Physiology (medical)
Internal medicine
Renin–angiotensin system
medicine
Animals
Muscle Strength
RNA, Messenger
Rats, Wistar
Sodium Chloride, Dietary
Receptor
Angiotensin II receptor type 1
business.industry
Angiotensin II
Myocardium
Body Weight
Adaptation, Physiological
Rats
Up-Regulation
Disease Models, Animal
Endocrinology
Hypertrophy, Left Ventricular
business
Angiotensin II Type 1 Receptor Blockers
medicine.drug
Subjects
Details
- ISSN :
- 15221490 and 03636119
- Volume :
- 295
- Database :
- OpenAIRE
- Journal :
- American Journal of Physiology-Regulatory, Integrative and Comparative Physiology
- Accession number :
- edsair.doi.dedup.....24ca5f25da59528247b340fcf7d80a85
- Full Text :
- https://doi.org/10.1152/ajpregu.00933.2007