Effect of streptozotocin-induced type 1 diabetes mellitus on contraction, calcium transient, and cation contents in the isolated rat heart.
Cations play major physiological and biochemical roles in the excitation-contraction coupling processes in the heart. This study investigated the effect of streptozotocin (STZ)-induced type I diabetes mellitus (DM) on contraction, calcium transient [Ca2+]i, and cation contents in the isolated rat heart compared to age-matched control. Diabetes rats weighed significantly (P < 0.05) less compared to control. They also had significantly (P < 0.05) elevated blood glucose compared to control. The whole heart, as well as the atria, right and left ventricles of the diabetic heart weighed significantly (P < 0.05) less compared to hearts from age control rats. The force of contraction and time to peak (t-pk) contraction in diabetic ventricular myocytes increased significantly (P < 0.05) compared to control. By contrast, these parameters did not change for the Ca2+ transient except for the time to half (t(1/2)) relaxation. The levels of sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), iron (Fe2+), copper (Cu2+), and zinc (Zn2+) in the hearts varied from diabetic compared to control animals. The results indicate that 6-8 weeks of STZ-induced DM is associated with marked changes in contraction and in cation contents of the heart. The delay in the t(1/2) relaxation of the Ca2+ transient may be responsible for the elevated contraction seen in the diabetic heart. Moreover, the changes in cation contents in the heart may be responsible for abnormal cardiac rhythms and activity during DM.
Singh
Jaipaul
J
Department of Biological and Forensic Sciences, University of Central Lancashire, Preston, Lancashire, PR1 2HE UK. jsingh3@uclan.ac.uk
Chonkar
Apurva
A
Bracken
Nicholas
N
Adeghate
Ernest
E
Latt
Zay
Z
Hussain
Munir
M
D000818:Animals; D001835:Body Weight; D002118:Calcium / Q000378:metabolism*; D002412:Cations / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism / Q000503:physiopathology*; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism / Q000503:physiopathology*; D006321:Heart / Q000033:anatomy & histology; D006325:Heart Atria / Q000033:anatomy & histology; D006352:Heart Ventricles / Q000033:anatomy & histology; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar
D002412:Cations; D002118:Calcium