Alterations in the regional beta adrenergic system in experimental left ventricular hypertrophy.

STUDY OBJECTIVE - The aim of the study was to determine the changes in the beta adrenergic system induced by cardiac hypertrophy due to valvular aortic stenosis. DESIGN - Density of beta adrenoceptors, cardiac tissue noradrenalime concentrations, coronary blood flow (using radioactive microspheres), and haemodynamic variables were compared in a model of experimental aortic valve stenosis of 6 month's duration and in sham operated controls. SUBJECTS - 14 mongrel dogs with aortic stenosis and eight sham operated litter mates were used in the studies.

Relationship between beta-adrenoceptors and coronary blood flow heterogeneity.

The purpose of this study was to investigate the hypothesis that the heterogeneous distribution of beta adrenoceptors contributes to the control of flow heterogeneity in the canine myocardium. beta adrenoceptor density and affinity were measured simultaneously with coronary blood flow in multiple sections of the left ventricle of 14 anesthetized open chest dogs. Radioactive microspheres were used for the measurement of blood flow.

Myocardial O2 supply and consumption in early cardiac hypertrophy of renal hypertensive rabbits.

This study examined myocardial O2 supply and O2 consumption in hypertension-induced myocardial hypertrophy. New Zealand white rabbits prepared as uninephrectomized (sham) controls (n = 7), or one kidney/one clip (1K1C) hypertensive rabbits (n = 7) were examined four weeks after surgery. A group of renally intact "true" controls (n = 4) was also examined.

Effect of reperfusion on O2 supply/consumption balance in ischemic canine left ventricle.

This study was designed to assess the effects of reperfusion on regional O2 supply and O2 consumption of ischemic areas of the myocardium in 15 anesthetized open-chested dogs. The left anterior descending coronary artery (LAD) was occluded for 6 h (n = 8), 2 h (n = 5), 2-h occlusion followed by 4-h period of reperfusion (n = 7), and 10-min occlusion followed by 90-min period of reperfusion (n = 3). Small artery and vein O2 saturations obtained microspectrophotometrically were combined with regional flow measurements using radioactive microspheres to determine regional myocardial O2 consumption.

Effects of propranolol on regional O2 supply and O2 consumption in reperfused dog myocardium.

This study was designed to assess whether propranolol would improve the relationship between O2 supply and O2 consumption in the reperfused ischemic dog myocardium. In 14 dogs, the left anterior descending coronary artery was occluded for 2 hr, followed by a 4-hr period of reperfusion. In 7 of the 14 dogs, 1 mg/kg of propranolol was administered 10 min before and again 2 hr after reperfusion.