Myocardial insulin resistance induced by high fat feeding in heart failure is associated with preserved contractile function.
Previous studies have reported that high fat feeding in mild to moderate heart failure (HF) results in the preservation of contractile function. Recent evidence has suggested that preventing the switch from fatty acid to glucose metabolism in HF may ameliorate dysfunction, and insulin resistance is one potential mechanism for regulating substrate utilization. This study was designed to determine whether peripheral and myocardial insulin resistance exists with HF and/or a high-fat diet and whether myocardial insulin signaling was altered accordingly. Rats underwent coronary artery ligation (HF) or sham surgery and were randomized to normal chow (NC; 14% kcal from fat) or a high-fat diet (SAT; 60% kcal from fat) for 8 wk. HF + SAT animals showed preserved systolic (+dP/dt and stroke work) and diastolic (-dP/dt and time constant of relaxation) function compared with HF + NC animals. Glucose tolerance tests revealed peripheral insulin resistance in sham + SAT, HF + NC, and HF + SAT animals compared with sham + NC animals. PET imaging confirmed myocardial insulin resistance only in HF + SAT animals, with an uptake ratio of 2.3 ± 0.3 versus 4.6 ± 0.7, 4.3 ± 0.4, and 4.2 ± 0.6 in sham + NC, sham + SAT, and HF + NC animals, respectively; the myocardial glucose utilization rate was similarly decreased in HF + SAT animals only. Western blot analysis of insulin signaling protein expression was indicative of cardiac insulin resistance in HF + SAT animals. Specifically, alterations in Akt and glycogen synthase kinase-3β protein expression in HF + SAT animals compared with HF + NC animals may be involved in mediating myocardial insulin resistance. In conclusion, HF animals fed a high-saturated fat exhibited preserved myocardial contractile function, peripheral and myocardial insulin resistance, decreased myocardial glucose utilization rates, and alterations in cardiac insulin signaling. These results suggest that myocardial insulin resistance may serve a cardioprotective function with high fat feeding in mild to moderate HF.
Christopher
Bridgette A
BA
Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106-4970, USA.
Huang
Hsuan-Ming
HM
Berthiaume
Jessica M
JM
McElfresh
Tracy A
TA
Chen
Xiaoqin
X
Croniger
Colleen M
CM
Muzic
Raymond F
RF
Chandler
Margaret P
MP
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D015153:Blotting, Western; D004041:Dietary Fats / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D004195:Disease Models, Animal; D015150:Echocardiography, Doppler; D004734:Energy Metabolism; D005951:Glucose Tolerance Test; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006333:Heart Failure / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology*; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D008297:Male; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D010766:Phosphorylation; D049268:Positron-Emission Tomography; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D013997:Time Factors; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
D001786:Blood Glucose; D004041:Dietary Fats; D007328:Insulin; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3