TY - JOUR
T1 - The effects of heavy long-term exercise on ventricular myocyte shortening and intracellular Ca2+ in streptozotocin-induced diabetic rat
AU - Howarth, Frank Christopher
AU - Almugaddum, Fadwa A.
AU - Qureshi, Muhammud A.
AU - Ljubisavljevic, Milos
N1 - Funding Information:
This study was supported by an Interdisciplinary Grant (01-03-8-12/06) from UAE University.
PY - 2010/7
Y1 - 2010/7
N2 - Objective: This study investigated whether exercise training, initiated at the onset of diabetes, could preserve the contractile properties of ventricular myocytes. Research Design and Methods: The effects of a heavy exercise training program on shortening and intracellular Ca2+ in unloaded ventricular myocytes from streptozotocin (STZ)-induced diabetic rats were examined. Animals were divided into four groups: control sedentary (CS), diabetic sedentary (DS), control heavy exercise (CHE), and diabetic heavy exercise (DHE). Exercise protocol: 5×60 min/week, 18 m/min, 5% gradient. Exercise training began 1 week after STZ treatment and continued for 12-23 (mean 17.5) weeks. Results: Diabetes induced prolongation of time-to-peak (TPK) shortening (124±2 ms in DS compared to 97±2 ms in CS rats), which was further increased by exercise (133±3 ms in DHE and 112±2 ms in CHE myocytes). Diabetes had no significant effects on time-to-half (THALF) relaxation of shortening (61±2 ms in DS compared to 56±2 ms in CS myocytes). Exercise induced significant prolongation of THALF in control (66±3 ms) but not in diabetic (69±3 ms) myocytes. Diabetes, though not exercise, significantly prolonged TPK (76±3 ms in DS compared to 64±2 ms in CS) and THALF recovery (160±5 ms in DS compared to 118±4 ms in CS) of the Ca2+ transient. Neither diabetes nor exercise had significant effects on the amplitude of myocyte shortening and the Ca2+ transient. Conclusions: Heavy long-term exercise alters the dynamics but not the amplitude of unloaded myocyte contraction in the STZ-induced diabetic rat.
AB - Objective: This study investigated whether exercise training, initiated at the onset of diabetes, could preserve the contractile properties of ventricular myocytes. Research Design and Methods: The effects of a heavy exercise training program on shortening and intracellular Ca2+ in unloaded ventricular myocytes from streptozotocin (STZ)-induced diabetic rats were examined. Animals were divided into four groups: control sedentary (CS), diabetic sedentary (DS), control heavy exercise (CHE), and diabetic heavy exercise (DHE). Exercise protocol: 5×60 min/week, 18 m/min, 5% gradient. Exercise training began 1 week after STZ treatment and continued for 12-23 (mean 17.5) weeks. Results: Diabetes induced prolongation of time-to-peak (TPK) shortening (124±2 ms in DS compared to 97±2 ms in CS rats), which was further increased by exercise (133±3 ms in DHE and 112±2 ms in CHE myocytes). Diabetes had no significant effects on time-to-half (THALF) relaxation of shortening (61±2 ms in DS compared to 56±2 ms in CS myocytes). Exercise induced significant prolongation of THALF in control (66±3 ms) but not in diabetic (69±3 ms) myocytes. Diabetes, though not exercise, significantly prolonged TPK (76±3 ms in DS compared to 64±2 ms in CS) and THALF recovery (160±5 ms in DS compared to 118±4 ms in CS) of the Ca2+ transient. Neither diabetes nor exercise had significant effects on the amplitude of myocyte shortening and the Ca2+ transient. Conclusions: Heavy long-term exercise alters the dynamics but not the amplitude of unloaded myocyte contraction in the STZ-induced diabetic rat.
KW - Cardiac muscle
KW - Diabetes mellitus
KW - Exercise training
KW - Ventricular myocytes
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U2 - 10.1016/j.jdiacomp.2009.03.001
DO - 10.1016/j.jdiacomp.2009.03.001
M3 - Article
C2 - 19395278
AN - SCOPUS:77953025590
SN - 1056-8727
VL - 24
SP - 278
EP - 285
JO - Journal of Diabetes and its Complications
JF - Journal of Diabetes and its Complications
IS - 4
ER -