Altered diaphragm muscle action potentials in Zucker diabetic fatty (ZDF) rats.
The Zucker diabetic fatty (ZDF) rat is a model of type 2 diabetes, being characterized by obesity, diabetes, and dyslipidemia. In vitro studies tested the hypothesis that diaphragm muscle from ZDF rats has abnormal resting membrane potential and action potentials, similar to type 1 diabetic rodents. Resting membrane potential was comparable for muscle from ZDF and control rats. Diaphragm from ZDF rats had augmented action potential peak height (92.1 mV versus 82.4 mV, P<0.00001), overshoot (15.6 mV versus 8.1 mV, P<0.001) and area (80.7 mV ms versus 68.6 mV ms, P<0.001) compared with that from controls. Action potential rate of depolarization and repolarization were not affected. The K(+) blocker, 3,4-diaminopyridine, augmented action potential duration and area of muscle from ZDF and controls, but without significant differences between animal groups. These findings in ZDF rats contrast with type 1 diabetic rats, suggesting that isolated hyperglycemia differs from hyperglycemia combined with other metabolic perturbations with respect to diaphragm electrophysiological derangements.
van Lunteren
Erik
E
Department of Medicine (Pulmonary and Critical Care Division), Cleveland VA Medical Center and Case Western Reserve University, 10701 East Boulevard, Cleveland, OH 44106, USA. exv4@cwru.edu
Moyer
Michelle
M
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000503:physiopathology*; D003964:Diaphragm / Q000502:physiology / Q000503:physiopathology*; D004195:Disease Models, Animal; D004594:Electrophysiology; D006943:Hyperglycemia / Q000150:complications; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D024821:Metabolic Syndrome / Q000150:complications / Q000503:physiopathology; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D051381:Rats; D011924:Rats, Zucker