Effect of endurance swimming on rat cardiac myofibrillar ATPase with experimental diabetes.
Diabetes is characterized by depressed cardiac functional properties attributed to Ca2+-activated ATPase activity. In contrast, endurance swimming enhances the cardiac functional properties and Ca2+-activated myofibril ATPase. Thus, the purpose of this study was to observe if the changes associated with experimental diabetes can be ameliorated with training. Diabetes was induced with a single i.v. injection of streptozotocin (60 mg/kg). Blood and urine glucose concentrations were 802 +/- 44 and 6965 +/- 617 mg/dL, respectively. The training control and training diabetic animals were made to swim (+/- 2% body weight) 4 days/week for 8 weeks. Cardiac myofibril, at 10 microM free Ca2+ concentration was reduced by 54% in the sedentary diabetics compared with sedentary control animals (p less than 0.05). Swim training enhanced the Ca2+-activated myofibril ATPase activities for the normal animals. The diabetic animals, which swam for 8 weeks, had further reduced their Ca2+-activated myofibril ATPase activity when compared with sedentary diabetics (p less than 0.05). Similarly, the Mg2+-stimulated myofibril ATPase activity was depressed by 31% in diabetics following endurance swimming. It is concluded that the depressed Ca2+-activated myofibril ATPase activity of diabetic hearts is not reversible with endurance swimming.
Belcastro
A N
AN
Maybank
P
P
Rossiter
M
M
Secord
D
D
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000201:enzymology*; D006321:Heart / Q000033:anatomy & histology; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D009210:Myofibrils / Q000201:enzymology*; D009929:Organ Size; D005082:Physical Exertion; D051381:Rats; D013550:Swimming
D001786:Blood Glucose; D000252:Calcium-Transporting ATPases