Type II diabetic mice exhibit contractile dysfunction but maintain cardiac output by favourable loading conditions.
BACKGROUND
Cardiomyopathy in type II diabetes is incompletely understood. The leptin receptor-deficient (db/db) mouse is a well-accepted model of type II diabetes. To date, left ventricular contractility has not been studied in animal models of type II diabetes with in vivo load-independent parameters.


OBJECTIVE
To determine cardiac function in db/db mice in vivo.


METHODS
Cardiac function in 12- and 24-week-old db/db and wild-type mice was assessed using a microtip-pressure-conductance catheter.


RESULTS
Left ventricular contractile dysfunction, measured by load-independent parameters (preload recruitable stroke work, end-systolic elastance, dP/dt-V(ed)), is present in diabetic mice from age 24 weeks onwards. Despite this contractile dysfunction, the conventional parameters cardiac output, ejection fraction and dP/dt(max) were maintained, which was due to an increased preload and decreased afterload. Ventriculo-arterial coupling was increased and mechanical efficiency significantly reduced in db/db mice.


CONCLUSIONS
Our results demonstrate that, despite impaired cardiac contractility and mechanical efficiency, cardiac output is maintained in db/db mice by favourable loading conditions and that in vivo load-independent measurements are necessary to fully characterize cardiac performance in animal models of pathophysiological states.
Van den Bergh
An
A
Laboratory of Experimental Cardiac Surgery, K.U. Leuven, Provisorium I, Minderbroedersstraat 17, 3000 Leuven, Belgium.
Flameng
Willem
W
Herijgers
Paul
P
D000818:Animals; D002302:Cardiac Output; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D051379:Mice; D009200:Myocardial Contraction