title: Effect of exercise training on Ca²⁺ release units of left ventricular myocytes of spontaneously hypertensive rats.
abstract: In cardiomyocytes, calcium (Ca²⁺) release units comprise clusters of intracellular Ca²⁺ release channels located on the sarcoplasmic reticulum, and hypertension is well established as a cause of defects in calcium release unit function. Our objective was to determine whether endurance exercise training could attenuate the deleterious effects of hypertension on calcium release unit components and Ca²⁺ sparks in left ventricular myocytes of spontaneously hypertensive rats. Male Wistar and spontaneously hypertensive rats (4 months of age) were divided into 4 groups: normotensive (NC) and hypertensive control (HC), and normotensive (NT) and hypertensive trained (HT) animals (7 rats per group). NC and HC rats were submitted to a low-intensity treadmill running protocol (5 days/week, 1 h/day, 0% grade, and 50-60% of maximal running speed) for 8 weeks. Gene expression of the ryanodine receptor type 2 (RyR2) and FK506 binding protein (FKBP12.6) increased (270%) and decreased (88%), respectively, in HC compared to NC rats. Endurance exercise training reversed these changes by reducing RyR2 (230%) and normalizing FKBP12.6 gene expression (112%). Hypertension also increased the frequency of Ca²⁺ sparks (HC=7.61 ± 0.26 vs NC=4.79 ± 0.19 per 100 µm/s) and decreased its amplitude (HC=0.260 ± 0.08 vs NC=0.324 ± 0.10 ΔF/F0), full width at half-maximum amplitude (HC=1.05 ± 0.08 vs NC=1.26 ± 0.01 µm), total duration (HC=11.51 ± 0.12 vs NC=14.97 ± 0.24 ms), time to peak (HC=4.84 ± 0.06 vs NC=6.31 ± 0.14 ms), and time constant of decay (HC=8.68 ± 0.12 vs NC=10.21 ± 0.22 ms). These changes were partially reversed in HT rats (frequency of Ca²⁺ sparks=6.26 ± 0.19 µm/s, amplitude=0.282 ± 0.10 ΔF/F0, full width at half-maximum amplitude=1.14 ± 0.01 µm, total duration=13.34 ± 0.17 ms, time to peak=5.43 ± 0.08 ms, and time constant of decay=9.43 ± 0.15 ms). Endurance exercise training attenuated the deleterious effects of hypertension on calcium release units of left ventricular myocytes.
authors.affiliation: Departamento de Ciências Fisiológicas, Universidade Federal do Espírito Santo, Vitória, ES, Brasil.
authors.forename: M A
authors.initials: MA
authors.lastname: Carneiro-Júnior
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brasil.
authors.forename: J F
authors.initials: JF
authors.lastname: Quintão-Júnior
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brasil.
authors.forename: L R
authors.initials: LR
authors.lastname: Drummond
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brasil.
authors.forename: V N
authors.initials: VN
authors.lastname: Lavorato
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brasil.
authors.forename: F R
authors.initials: FR
authors.lastname: Drummond
authors.affiliation: Laboratório de Bioquímica e Biologia Molecular do Exercício, Escola de Educação Física e Esportes, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: M A
authors.initials: MA
authors.lastname: Amadeu
authors.affiliation: Laboratório de Bioquímica e Biologia Molecular do Exercício, Escola de Educação Física e Esportes, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: E M
authors.initials: EM
authors.lastname: Oliveira
authors.affiliation: Departamento de Engenharia Elétrica, Universidade Federal de Viçosa, Viçosa, MG, Brasil.
authors.forename: L B
authors.initials: LB
authors.lastname: Felix
authors.affiliation: Laboratório de Membranas Excitáveis e Biologia Cardiovascular, Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
authors.forename: J S
authors.initials: JS
authors.lastname: Cruz
authors.affiliation: Departamento de Ciências Fisiológicas, Universidade Federal do Espírito Santo, Vitória, ES, Brasil.
authors.forename: J G
authors.initials: JG
authors.lastname: Mill
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brasil.
authors.forename: A J
authors.initials: AJ
authors.lastname: Natali
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brasil.
authors.forename: T N
authors.initials: TN
authors.lastname: Prímola-Gomes
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D005080:Exercise Test / Q000379:methods; D006352:Heart Ventricles / Q000166:cytology / Q000378:metabolism*; D006973:Hypertension / Q000378:metabolism / Q000628:therapy*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000379:methods*; D011918:Rats, Inbred SHR; D017208:Rats, Wistar; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism; D022021:Tacrolimus Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D019837:Ryanodine Receptor Calcium Release Channel; D022021:Tacrolimus Binding Proteins; C403484:tacrolimus binding protein 1B; D002118:Calcium