The dual radionuclide myocardial distributions of imaging agents potassium43 (49K) and technetium-99m stannous pyrophosphate ('9mTc-PYP) were studied in a 24-hour closed chest canine infarct preparation. In multiple myocardial biopsies in 20 dogs, tissue levels of both radionuclides were compared to either an index of tissue viability (myocardial creatine phosphokinase [CPK] depletion), or to e...

AIMS The aim of this animal study is to assess fasting-induced changes in myocardial substrate metabolism and energy status as a consequence of mitochondrial long-chain fatty acid β-oxidation deficiency, using magnetic resonance spectroscopy (MRS). METHODS AND RESULTS Carbon-13 ((13)C) MRS of hyperpolarized [1-(13)C]pyruvate was used to assess in vivo pyruvate dehydrogenase (PDH) activity in ...

We applied a nondestructive tracer technique, previously developed for measuring skeletal muscle protein turnover, to the measurement of myocardial protein turnover in vivo. During a continuous infusion of L-[ring-2,6-3H]phenylalanine to anesthetized, overnight-fasted dogs, we measured the uptake of radiolabeled phenylalanine from plasma and the release of unlabeled phenylalanine from myocardia...

To analyze the specificity of the diffuse pattern of cardiac uptake with technetium-99m stannous pyrophosphate (TcPYP), we evaluated the bone scans of 1,383 noncardiac patients and the myocardial scintigrams of 120 cardiac patients. Seventy (14.4%) of 483 bone scans performed on a scintillation camera revealed diffuse TcPYP cardiac uptake. Among the total 603 camera bone scans and myocardial sc...

It is not known whether myocardial energy requirements can be increased to the degree that they exceed myocardial O2 availability in the absence of abnormalities of coronary blood flow or coronary reserve. To determine whether this form of "demand ischemia" occurs, 10 swine were subjected to pressure overload induced by aortic constriction, inotropic and chronotropic stimulation by dobutamine, ...

Ten patients with chronic effort angina and coronary artery disease (luminal diameter reduction greater than 75%) were stressed by atrial pacing (140 beats/minutes) before and 15 minutes after intravenous propranolol (mean dose 7.4 mg). Myocardial substrate exchange of oxygen, blood lactate, plasma free fatty acids, citrate, glucose, glutamate, and alanine as well as coronary sinus blood flow w...

Glucose uptake appears preserved or even enhanced in the chronically dysfunctional but viable myocardium. However, the use of other fuels such as free fatty acids (FFA) remains unknown. We studied FFA uptake in the chronically dysfunctional but viable myocardium in seven patients with an occluded major coronary artery and a corresponding chronic wall motion abnormality but no previous infarctio...

Regional myocardial perfusion and exogenous glucose uptake were assessed with rubidium-82 (82Rb) and 18F-2-fluoro-2-deoxyglucose (FDG) in 10 normal volunteers and 12 patients with coronary artery disease and stable angina pectoris by means of positron emission tomography. In patients at rest, the myocardial uptake of 82Rb and FDG did not differ significantly from that measured in normal subject...

Cardiac muscle is characterized by insulin resistance in specific heart diseases such as coronary artery disease and congestive heart failure, but not in generalized disorders like diabetes mellitus and essential hypertension when cardiac manifestations are absent. To examine whether the insulin antagonistic effect of growth hormone (GH) acts upon the heart, we compared insulin-stimulated whole...