Exercise training increases myocardial inotropic response in food restricted rats.
This study evaluated the effects of exercise training on myocardial function and ultrastructure of rats submitted to different levels of food restriction (FR). Male Wistar-Kyoto rats, 60 days old, were submitted to free access to food, light FR (20%), severe FR (50%) and/or to swimming training (one hour per day with 5% of load, five days per week for 90 days). Myocardial function was evaluated by left ventricular papillary muscle under basal condition (calcium 1.25 mM), and after extracellular calcium elevation to 5.2 mM and isoproterenol (1 microM) addition. The ultrastructure of the myocardium was examined in the papillary muscle. The training effectiveness was verified by improvement of myocardial metabolic enzyme activities. Both 20% and 50% food restriction protocols presented minor body and ventricular weights gain. The 20%-FR, in sedentary or trained rats, did not alter myocardial function or ultrastructure. The 50%-FR, in sedentary rats, caused myocardial dysfunction under basal condition, decreased response to inotropic stimulation, and promoted myocardial ultrastructural damage. The 50%-FR, in exercised rats, increased myocardial dysfunction under basal condition but increased response to inotropic stimulation although there was myocardial ultrastructural damage. In conclusion, the exercise training in severe restriction caused marked myocardial dysfunction at basal condition but increased myocardial response to inotropic stimulation.
Sugizaki
Mario Mateus
MM
Department of Internal Medicine, School of Medicine, State University Júlio, Mesquita Filho, UNESP, Botucatu, São Paulo, Brazil.
Dal Pai-Silva
Maeli
M
Carvalho
Robson Francisco
RF
Padovani
Carlos Roberto
CR
Bruno
Alessandro
A
Nascimento
André Ferreira
AF
Aragon
Flávio Ferrari
FF
Novelli
Ethel Lourenzi Barbosa
EL
Cicogna
Antonio Carlos
AC
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005508:Food Deprivation / Q000502:physiology*; D006321:Heart / Q000502:physiology*; D007545:Isoproterenol / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D010210:Papillary Muscles / Q000648:ultrastructure*; D010805:Physical Conditioning, Animal; D010807:Physical Endurance / Q000502:physiology; D051381:Rats; D011921:Rats, Inbred WKY; D012508:Sarcolemma / Q000648:ultrastructure
D000318:Adrenergic beta-Agonists; D002316:Cardiotonic Agents; D015094:3-Hydroxyacyl CoA Dehydrogenases; D007770:L-Lactate Dehydrogenase; D002950:Citrate (si)-Synthase; D007545:Isoproterenol