Search PubMed⌕ Search

Biomedical subjects

J Barmeyer

Publications and source records attributed to J Barmeyer.

106 records · Page 6Linked to original sources
PubMedDate not supplied

Myocardial oxygen consumption and substrate uptake in man during physiological and pathological volume load.

It is shown in trained and untrained healthy individuals that the energy requirement of the physiologically hypertrophied heart is lower at rest and even more pronounced during submaximal heavy exercise compared to the non-hypertrophied state. This difference exceeds the changes which could have been anticipated by deviations in hemodynamics and total heart weight. In patients with mild or moderate aortic insufficiency the energy expenditure of the pathologically hypertrophied heart per unit tissue mass is comparable to the non-hypertrophied state at rest or during exercise. It is increased in severe aortic regurgitation or additional myocarditis. The transition from compensation to failure may be associated with a steep decreased of the metabolic and flow reserve of the whole heart.

Cardiomegaly↗
PubMedDate not supplied

Studies on the regulation of myocardial blood flow in man. I.: Training effects on blood flow and metabolism of the healthy heart at rest and during standardized heavy exercise.

In a comparative study 11 athletes and 11 untrained students were investigated at rest, of these 6 trained and 5 untrained individuals during exercise as well. Myocardial blood flow was measured by the argon method. Myocardial oxygen consumption, myocardial substrate uptake of glucose, lactate, and free fatty acids and cardiac output were determined by the direct Fick principle. Exercise was standardized according to 65% of an individual's maximal oxygen uptake (delta VO2 max). Coronary flow reserve was determined by dipyridamole injections. All measurements were made during hemodynamic and respiratory steady-state conditions with the subject in a supine position. At rest, myocardial blood flow and myocardial oxygen consumption were significantly lower in trained subjects compared to the untrained ones. These differences were more pronounced during heavy exercise. They cannot be explained completely by hemodynamic parameters. - During exercise, myocardial substrate uptake shifted to a predominant lactate uptake of almost 90% of total substrate uptake. Total substrate uptake as well as lactate uptake correlated significantly with myocardial oxygen. - Coronary flow reserve was lower in the trained group. It is concluded that the heart muscle of a trained individual requires less energy at a given work load than in the untrained state.

Adult↗