Exercise training prevents beta-adrenergic hyperactivity-induced myocardial hypertrophy and lesions.
BACKGROUND
Sustained beta-adrenoreceptor activation promotes cardiac hypertrophy and cellular injury.


OBJECTIVE
To evaluate the cardioprotective effect of exercise on damage induced by beta-adrenergic hyperactivity.


METHODS
Male Wistar rats were randomised into four groups (n=8 per group): sedentary non-treated control (C), sedentary treated with isoproterenol 0.3 mg/kg/day administered subcutaneously for 8 days (I), exercised non-treated (E) and exercised plus isoproterenol administered during the last eight days of exercise (IE). Exercised animals ran on a treadmill for 1 h daily 6 times a week for 13 weeks.


RESULTS
Isoproterenol caused increases in left ventricle (LV) wet and dry weight/body weight ratio, LV water content and cardiomyocyte transverse diameter. Additionally, isoproterenol induced severe cellular lesions, necrosis, and apoptosis, increased collagen content and reduced capillary and fibre fractional areas. Notably, all of these abnormalities were completely prevented by exercise.


CONCLUSIONS
Our data have demonstrated that complete cardioprotection is possible through exercise training; by preventing beta-adrenergic hyperactivity-induced cardiac hypertrophy and structural injury.
Serra
Andrey J
AJ
Department of Medicine, Cardiology Division, Federal University of São Paulo, Brazil.
Higuchi
Maria L
ML
Ihara
Silvia S M
SS
Antônio
Ednei L
EL
Santos
Marília H H
MH
Bombig
Maria T N M
MT
Tucci
Paulo J F
PJ
D000318:Adrenergic beta-Agonists / Q000009:adverse effects*; D000818:Animals; D006332:Cardiomegaly / Q000209:etiology / Q000473:pathology* / Q000517:prevention & control*; D006333:Heart Failure / Q000209:etiology / Q000503:physiopathology / Q000628:therapy; D020287:In Situ Nick-End Labeling; D007545:Isoproterenol / Q000009:adverse effects*; D008297:Male; D010805:Physical Conditioning, Animal; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*
D000318:Adrenergic beta-Agonists; D011943:Receptors, Adrenergic, beta; D007545:Isoproterenol