Does early stage diabetes induce an adaptation of contractile machinery in female rats

Several evidences have suggested that there is a gender bias in the progression of diabetic cardiomyopathy. Indeed, premeopausal women frequently have a shorter risk of cardiovascular diseases than age-matched men and postmenopausal women. We investigated in female diabetic rats, whether altered myocardial function was related to changes in actomyosin interactions and if these modifications were attributable to a possible sarcomere rearrangement. Experiments were carried out on papillary muscles from diabetic female Wistar and age-matched control rats. Isometric and isotonic parameters, introduced into Huxley’s model, allowed to calculate mechanics, kinetics and energetics of myosin crossbridges. Sarcomere length was measured on TEM micrographs. Surprisingly, higher crossbridges number and lower unitary force were observed in diabetic rats. Histological and ultrastructural studies revealed fewer and longer sarcomeres in diabetic animals. Although the early signs of diabetic cardiomyopathy were well expressed, these findings suggested that in early stage of diabetes, female rats would show a compensatory mechanism to ensure an adequate stroke volume and a preserved cardiac performance.