title: Canine cardiac sarcoplasmic reticulum is not altered with endurance exercise training.
abstract: To investigate the effect of exercise training on calcium movements by isolated cardiac sarcoplasmic reticulum (SR), mongrel dogs either remained sedentary (S) or were exercise-trained (E) via running for a period of 8-10 wk. The trained state was confirmed by the increase in skeletal muscle citrate synthase activity and decreases in submaximal exercise heart rates in the E group but not in the S dogs. The properties of isolated cardiac SR were identical between the groups. The variables tested included ATP-dependent calcium transport and calcium-stimulated ATPase activity. Importantly, there was no difference in spontaneous calcium release which occurred after peak ATP-dependent calcium accumulation was reached. Calcium release from passively loaded vesicles induced by calcium and ionophore also did not differ in the SR isolated from the E dogs. The change in the affinity of the SR Ca ATPase for calcium after the addition of the polyanion, heparin, was similar in both groups, indicating that the regulation of calcium-stimulated ATPase activity by the SR protein, phospholamban, is not modified by exercise training. We conclude that exercise training of 8-10 wk duration does not alter the calcium handling properties of cardiac SR isolated from mongrel dogs.
authors.affiliation: Department of Medicine, Baylor College of Medicine, Houston, TX 77030.
authors.forename: C
authors.initials: C
authors.lastname: Tate
authors.forename: M
authors.initials: M
authors.lastname: Hamra
authors.forename: G
authors.initials: G
authors.lastname: Shin
authors.forename: G
authors.initials: G
authors.lastname: Taffet
authors.forename: P
authors.initials: P
authors.lastname: McBride
authors.forename: M
authors.initials: M
authors.lastname: Entman
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D004285:Dogs; D005260:Female; D006321:Heart / Q000502:physiology*; D008297:Male; D009206:Myocardium / Q000648:ultrastructure; D010805:Physical Conditioning, Animal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D012519:Sarcoplasmic Reticulum / Q000502:physiology*
chemical_list: D000252:Calcium-Transporting ATPases; D002118:Calcium