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Effect of Streptozotocin‐Induced Type 1 Diabetes Mellitus on Contraction, Calcium Transient, and Cation Contents in the Isolated Rat Heart
Author(s) -
SINGH JAIPAUL,
CHONKAR APURVA,
BRACKEN NICHOLAS,
ADEGHATE ERNEST,
LATT ZAY,
HUSSAIN MUNIR
Publication year - 2006
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1372.028
Subject(s) - streptozotocin , contraction (grammar) , calcium , diabetes mellitus , medicine , endocrinology , cardiology , chemistry
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 [Ca 2+ ] 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 Ca 2+ transient except for the time to half (t½) relaxation. The levels of sodium (Na + ), potassium (K + ), calcium (Ca 2+ ), magnesium (Mg 2+ ), iron (Fe 2+ ), copper (Cu 2+ ), and zinc (Zn 2+ ) 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 t½ relaxation of the Ca 2+ 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.