Oxygen and coronary vascular resistance during autoregulation and metabolic vasodilation in the dog.
AUTOR(ES)
Drake-Holland, A J
RESUMO
The hypothesis that tissue oxygen tension controls coronary vascular resistance during changes in perfusion pressure and oxygen consumption was expressed in a simplified mathematical form capable of making quantitative predictions. The predictive value of this formulation of the hypothesis was tested in experiments on anaesthetized mongrel dogs subjected to constant-pressure perfusion of the left main coronary artery, with measurements of coronary blood flow and arterio-venous oxygen content differences. Coronary venous oxygen content was used as an index of tissue oxygenation. The responses of coronary blood flow and arterio-venous oxygen content difference, made over a range of perfusion pressures (which caused autoregulation) and heart rates (which caused metabolic regulation) were predicted qualitatively by the model. Coronary vascular conductance was positively related to metabolic rate only during metabolic regulation (heart rate changes); during autoregulation the relationship between these two variables was inverse. Coronary vascular conductance and resistance values taken from both interventions (both perfusion pressure and heart rate variations) were closely related to coronary venous oxygen content and calculated PO2. These findings suggest that further examination of oxygen tension, as the controller of the coronary vascular bed under physiological conditions should be considered.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1199402Documentos Relacionados
- Vascular changes during penile erection in the dog.
- Lung reflexes and nasal vascular resistance in the anaesthetized dog.
- Parasympathetic nervous control of tracheal vascular resistance in the dog.
- Myocardial Blood Flow Distribution during Ischemia-Induced Coronary Vasodilation in the Unanesthetized Dog
- Peripheral collateral blood flow and vascular reactivity in the dog.