In healthy coronary smooth muscle cells, the superficial sarcoplasmic reticulum (SR) buffers rise in intracellular Ca2+ levels. In diabetic dyslipidemia, basal Ca2+ levels are increased, yet Ca 2+ influx is decreased and SR Ca2+ uptake is increased. Exercise prevents diabetic dyslipidemia-induced increases in basal Ca 2+ levels and decreases in Ca2+ influx. We tested the hypothesis that diabetic dyslipidemia impairs Ca2+ extrusion via a decrease in superficial SR and that exercise will prevent these losses. Male Yucatan swine were maintained in four treatment groups: control, hyperlipidemic, diabetic dyslipidemic, and diabetic dyslipidemic plus aerobically exercise trained. Intracellular Ca2+ levels were measured during depolarization-induced Ca2+ influx and caffeine-induced SR Ca 2+ release. Na+/Ca2+ exchanger and plasmalemmal Ca2+-ATPase activity were assessed by inhibition with low extracellular Na+ and 5,6-carboxyeosin, respectively. Superficial SR was quantified using the internal membrane dye 3,3′-dihexyloxacarbocyanine iodide (DiOC6) and novel analysis techniques. We found that, in diabetic dyslipidemia, Ca2+ extrusion was impaired and superficial SR was decreased. Exercise prevented the diabetic dyslipidemia-induced decrease in superficial SR and restored plasmalemrnal Ca2+ extrusion. On the basis of these results, we conclude exercise attenuates the diabetic dyslipidemia-induced impairment in intracellular Ca 2+ regulation.
- Plasma membrane calcium-adenosine-triphosphatase
- Sarco(endo)plasmic reticulum calcium-transporting adenosinetriphosphatase
- Sodium-calcium exchanger
ASJC Scopus subject areas
- Physiology (medical)