Search Results - (Author, Cooperation:S. F. Vatner)

2011-03-19

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Actin Cytoskeleton/metabolism ; Actins/metabolism ; Adenosine Triphosphatases/metabolism ; Adenosine Triphosphate/metabolism ; Adrenergic beta-Agonists/pharmacology ; Allosteric Regulation ; Animals ; Binding Sites ; Calcium/metabolism ; Cardiac Myosins/chemistry/*metabolism ; Cardiac Output/drug effects ; Dogs ; Female ; Heart Failure, Systolic/*drug therapy/physiopathology ; Isoproterenol/pharmacology ; Male ; Myocardial Contraction/*drug effects ; Myocytes, Cardiac/*drug effects/physiology ; Phosphates/metabolism ; Protein Binding ; Protein Conformation ; Protein Isoforms/chemistry/metabolism ; Rats ; Rats, Sprague-Dawley ; Urea/*analogs & derivatives/chemistry/metabolism/pharmacology ; Ventricular Function, Left/drug effects

1435-1803

LV function ; coronary stenosis ; coronary collaterals ; myocardial blood flow ; stunned myocardium

Springer Online Journal Archives 1860-2000

Medicine

Abstract Inotropic reserve, demonstrated with administration of sympathomimetic amines, is characteristic of hibernating myocardium. The goal of this study was to determine whether inotropic reserve was present following chronic coronary artery constriction in the pig, which is one potential model of hibernating myocardium. The effects of isoproterenol were examined in five conscious pigs 21±2.1 days after ameroid implantation on the left circumflex coronary artery on measurements of left ventricular (LV) pressure, LV dP/dt, and regional wall thickening in the ameroid-dependent zone (posterior wall) and contralateral non-ischemic zone (anterior wall). Isoproterenol, 0.1 μg/kg/min, increased LV dP/dt by 96±11%, heart rate by 43±13 beats/min, and normalized systolic wall thickening, slightly, but not significantly more in the ameroid-dependent zone (+1.57±0.31 mm) than in the contralateral non-ischemic zone (+1.04±031 mm), although the baseline wall thickening was reduced significantly in the ameroid-dependent zone. This occurred at a time when baseline myocardial blood flow was preserved and myocardial perfusion in the ameroid-dependent zone was derived in part from the native coronary circulation and also through collateral channels. Two weeks later histological evidence of lesions characteristics of hibernating myocardium, i.e., myofibrolysis and increased glycogen deposition, were observed. Thus, these histological changes and the confluence of chronically depressed regional function and residual inotropic reserve in the conscious pig with chronic ameroid-induced coronary constriction support this model for further study of hibernating myocardium.

Electronic Resource

1435-1803

alpha adrenergic receptors ; beta adrenergic receptors ; coronary blood flow ; coronary diameter

Springer Online Journal Archives 1860-2000

Medicine

Summary The effects of α and β adrenergic stimulation were examined in conscious dogs on measurements of left circumflex coronary blood flow and coronary arterial diameter and on calculations of mean coronary resistance (MCR) and left circumflex coronary internal cross-sectional area (CSA). Methoxamine (50 μg/kg/min), after transiently increasing left circumflex coronary dimensions, induced sustained reductions in left circumflex coronary diameter (9±2%) and CSA (27±5%) at a time when mean arterial pressure rose by 65±5%, left ventricular (LV) dP/dt had decreased only slightly, and heart rate and mean coronary blood flow were at control levels. Isoproterenol, (0.1 μg/kg/min), increased heart rate by 66±8%, LV dP/dt by 58±5%, and CSA by 17±3%, while it decreased mean arterial pressure by 12±1% and MCR by 44±5%. After β1 adrenergic receptor blockade and with heart rate held constant, isoproterenol did not increase LV dP/dt but decreased mean arterial pressure similarly (13±2%) and induced attenuated increases in CSA (6±1%), and decreases in MCR (17±3%). After combined β1 and β2 adrenergic receptor blockades isoproterenol induced no significant effects. Thus, in the conscious dog, large coronary vessels not only react passively to changes in aortic pressure but also undergo substantial active changes. Alpha adrenergic stimulation is sufficiently powerful to reduce CSA, despite the opposing elevation of distending pressure. Moreover, large vessels appear to be regulated by α1 adrenergic mediated increase in myocardial metabolic demands, as well as by α2 adrenergic mediated vasodilation.

Electronic Resource

1435-1803

Stunning ; hibernation ; ischemia

Springer Online Journal Archives 1860-2000

Medicine

Abstract We observed over two decades ago that myocardium rendered ischemic, but not irreversibly damaged, exhibited prolonged depression of regional myocardial function, long after the complete return of blood flow and resumption of a normal electrocardiographic pattern (3). At that time we did not appreciate the extent to which this characteristic of ischemic myocardium would be involved mechanistically in so many experimental and clinical settings. With the additional work of Kloner and Braunwald, the phenomenon of delayed recovery of postischemic tissue became known as “stunned myocardium” (2).

Electronic Resource