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Loss of bradykinin signaling does not accelerate the development of cardiac dysfunction in type 1 diabetic akita mice.

Authors Wende AR, Soto J, Olsen CD, Pires KM, Schell JC, Larrieu-Lahargue F, Litwin SE, Kakoki M, Takahashi N, Smithies O, Abel ED Submitted By Oliver Smithies on 5/2/2011 Status Published Journal Endocrinology Year 2010 Date Published 8/1/2010 Volume : Pages 151 : 3536 - 3542 PubMed Reference 20501666 Abstract Bradykinin signaling has been proposed to play either protective or deleterious roles in the development of cardiac dysfunction in response to various pathological stimuli. To further define the role of bradykinin signaling in the diabetic heart, we examined cardiac function in mice with genetic ablation of both bradykinin B1 and B2 receptors (B1RB2R(-/-)) in the context of the Akita model of insulin-deficient type 1 diabetes (Ins2(Akita/+)). In 5-month-old diabetic and nondiabetic, wild-type and B1RB2R(-/-) mice, in vivo cardiac contractile function was determined by left-ventricular (LV) catheterization and echocardiography. Reactive oxygen species levels were measured by 2'-7'-dichlorofluorescein diacetate fluorescence. Mitochondrial function and ATP synthesis were determined in saponin-permeabilized cardiac fibers. LV systolic pressure and the peak rate of LV pressure rise and decline were decreased with diabetes but did not deteriorate further with loss of bradykinin signaling. Wall thinning and reduced ejection fractions in Akita mouse hearts were partially attenuated by B1RB2R deficiency, although other parameters of LV function were unaffected. Loss of bradykinin signaling did not increase fibrosis in Ins2(Akita/+) diabetic mouse hearts. Mitochondrial dysfunction was not exacerbated by B1RB2R deficiency, nor was there any additional increase in tissue levels of reactive oxygen species. Thus, loss of bradykinin B2 receptor signaling does not abrogate the previously reported beneficial effect of inhibition of B1 receptor signaling. In conclusion, complete loss of bradykinin expression does not worsen cardiac function or increase myocardial fibrosis in diabetes.

Investigators with authorship
Name Institution E. Dale Abel University of Iowa Oliver Smithies University of North Carolina Nobuyuki Takahashi Tohoku University

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