The role of coronary flow and pressure as determinants of myocardial oxygen consumption in the presence or absence of vasomotor tone

1977 ◽  
Vol 55 (3) ◽  
pp. 471-477 ◽  
Author(s):  
D. T. Zborowska-Sluis ◽  
R. R. Mildenberger ◽  
G. A. Klassen
Keyword(s):  
Oxygen Consumption ◽  
Coronary Flow ◽  
Myocardial Oxygen Consumption ◽  
Important Determinant ◽  
Significant Alteration ◽  
Oxygen Extraction ◽  
Vasomotor Tone ◽  
Coronary Pressure

When coronary flow was kept constant and coronary pressure increased by angiotensin or decreased by dipyridamole, myocardial oxygen consumption (MVO2) remained unchanged. When vasomotor tone was abolished by dipyridamole or was intact, changing coronary flow resulted in a change in MVO2 in the same direction as flow; this change in MVO2 was in part the result of a significant alteration in coronary oxygen extraction. These results suggest that coronary flow, but not coronary pressure is an important determinant of MVO2 both in the presence or absence of vasomotor tone.

Effect of pericoronary denervation on coronary hemodynamics

1960 ◽  
Vol 199 (1) ◽  
pp. 174-178 ◽  
Author(s):  
Norman Brachfeld ◽  
R. Grier Monroe ◽  
Richard Gorlin
Keyword(s):  
Oxygen Consumption ◽  
Coronary Flow ◽  
Myocardial Oxygen Consumption ◽  
Relative Increase ◽  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Concomitant Increase ◽  
Oxygen Extraction Ratio ◽  
Coronary Vasoconstriction

In a series of 15 dogs, the procedure of pericoronary neurectomy resulted in a relative increase in coronary flow and decrease in oxygen extraction. This was best illustrated by a decrease in coefficient of oxygen extraction (A-V)OO2/AOO2 and was suggested by an increase in coronary flow/oxygen extraction ratio relative to oxygen consumption. It is concluded that at rest the net result of neurogenic impulses (both sympathetic and parasympathetic) is some degree of coronary vasoconstriction. Following denervation, this constrictor tonus is lost and there is a concomitant increase in coronary flow for a given myocardial oxygen consumption.

Myocardial oxygen consumption: the role of wall force and shortening

1977 ◽  
Vol 233 (4) ◽  
pp. H421-H430 ◽  
Author(s):  
K. T. Weber ◽  
J. S. Janicki
Keyword(s):  
Coronary Flow ◽  
Myocardial Oxygen Consumption ◽  
Left Ventricular ◽  
Steady State Response ◽  
State Response ◽  
Predominant Factor ◽  
Myocardial O2 Consumption ◽  
The Relationship ◽  
Oxygen Difference

The relationship between the force in the left ventricular wall during systole and myocardial O2 consumption (MVO2) was determined. In addition, the relative influence of the load imposed during shortening and fiber shortening on MVO2 was assessed. For this purpose, 14 servo-regulated, paced, isolated canine hearts were used and the steady-state response in total coronary flow and arteriovenous oxygen difference was measured. For both the isovolumetrically beating and the ejecting ventricle, statistically significant linear relations were observed between MVO2 and the integral of systolic force. These relations were not significantly different from one another, indicating that shortening was not a determinant of MVO2. Moreover, when ejecting an isolumetric beats of equivalent developed force were compared, a difference in MVO2 (deltaMVO2) was found. deltaMVO2 was a function of the force integral difference between these contractions and not fiber shortening. Thus, under the conditions of this experiment, the integral of systolic force that includes developed force and shortening load is the predominant factor regulating MVO2 for any given contractile state, whereas the influence of fiber shortening is negligible.

Nitric oxide modulates epicardial coronary basal vasomotor tone in awake dogs

1990 ◽  
Vol 258 (4) ◽  
pp. H1250-H1254 ◽  
Author(s):  
A. Chu ◽  
D. E. Chambers ◽  
C. C. Lin ◽  
W. D. Kuehl ◽  
F. R. Cobb
Keyword(s):  
Nitric Oxide ◽  
Coronary Flow ◽  
Diastolic Pressure ◽  
Coronary Vessels ◽  
Aortic Pressure ◽  
Left Ventricular ◽  
Vasomotor Tone ◽  
Coronary Vasomotor Tone ◽  
Endogenous Nitric Oxide

This study evaluates the role of endogenous nitric oxide in the modulation of basal coronary vasomotor tone by studying the effects of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of nitric oxide formation from L-arginine, on resting epicardial coronary diameter and coronary flow. L-NMMA (5 mg/kg) was infused in seven awake dogs chronically instrumented with coronary dimension crystals for measurement of epicardial coronary diameter, and Doppler flow probes for quantitation of phasic coronary flow (vasomotion of distal regulatory resistance coronary vessels). Epicardial coronary diameter decreased 5.5% from 3.47 +/- 0.17 to 3.28 +/- 0.15 mm (mean +/- SE). The diameter change was gradual, reaching a maximum at 13 +/- 2 min after infusion, and persistent, lasting greater than 90 min. Phasic coronary flow did not change. Mean aortic pressure significantly increased from 99 +/- 3 to 111 +/- 3 mmHg and heart rate decreased from 56 +/- 4 to 46 +/- 3 beats/min. Left ventricular end-diastolic pressure and contractility were not significantly altered. L-Arginine (66 mg/kg) but not D-arginine reversed all hemodynamic parameters. These data support an important role of nitric oxide in modulating basal epicardial coronary vasomotor tone and systemic vascular resistance.

Is Calcium a Coronary Vasoconstrictor In Vivo? 

1998 ◽  
Vol 88 (3) ◽  
pp. 735-743 ◽  
Author(s):  
George J. Crystal ◽  
Xiping Zhou ◽  
Ramez M. Salem
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Coronary Blood Flow ◽  
Myocardial Oxygen Consumption ◽  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Oxygen Extraction Ratio ◽  
Myocardial Oxygen Extraction ◽  
Dose Dependent

Background Calcium produces constriction in isolated coronary vessels and in the coronary circulation of isolated hearts, but the importance of this mechanism in vivo remains controversial. Methods The left anterior descending coronary arteries of 20 anesthetized dogs whose chests had been opened were perfused at 80 mmHg. Myocardial segmental shortening was measured with ultrasonic crystals and coronary blood flow with a Doppler flow transducer. The coronary arteriovenous oxygen difference was determined and used to calculate myocardial oxygen consumption and the myocardial oxygen extraction ratio. The myocardial oxygen extraction ratio served as an index of effectiveness of metabolic vasodilation. Data were obtained during intracoronary infusions of CaCl2 (5, 10, and 15 mg/min) and compared with those during intracoronary infusions of dobutamine (2.5, 5.0, and 10.0 microg/min). Results CaCl2 caused dose-dependent increases in segmental shortening, accompanied by proportional increases in myocardial oxygen consumption. Although CaCl2 also increased coronary blood flow, these increases were less than proportional to those in myocardial oxygen consumption, and therefore the myocardial oxygen extraction ratio increased. Dobutamine caused dose-dependent increases in segmental shortening and myocardial oxygen consumption that were similar in magnitude to those caused by CaCl2. In contrast to CaCl2, however, the accompanying increases in coronary blood flow were proportional to the increases in myocardial oxygen consumption, with the result that the myocardial oxygen extraction ratio remained constant. Conclusions Calcium has a coronary vasoconstricting effect and a positive inotropic effect in vivo. This vasoconstricting effect impairs coupling of coronary blood flow to the augmented myocardial oxygen demand by metabolic vascular control mechanisms. Dobutamine is an inotropic agent with no apparent direct action on coronary resistance vessels in vivo.

Effect of changes in blood CO2 level on coronary flow and myocardial O2 consumption

1960 ◽  
Vol 199 (2) ◽  
pp. 349-354 ◽  
Author(s):  
H. Feinberg ◽  
A. Gerola ◽  
L. N. Katz
Keyword(s):  
Oxygen Consumption ◽  
Coronary Flow ◽  
Myocardial Oxygen Consumption ◽  
Gas Mixture ◽  
Aortic Blood ◽  
Anesthetized Dogs ◽  
Myocardial O2 Consumption ◽  
Aortic Blood Pressure ◽  
Co2 Level ◽  
Oxygen Difference

The effect of hypo- and hypercapnia—induced by changing the respiratory gas mixture—on coronary flow and myocardial oxygen consumption was observed at constant cardiac output and over a broad range of pressure-loads in open-chested, anesthetized dogs. The correlation of cardiac effort (as indexed by the product of heart rate and mean aortic blood pressure) with myocardial oxygen consumption was not altered by increasing or decreasing the arterial CO2 content. Coronary blood flow was observed to be increased relative to the cardiac effort during hypercapnia but not during hypocapnia. The coronary arteriovenous oxygen difference and the percentage of oxygen extracted decreased during hypercapnia pari passu with the increase in venous oxygen content.

Effect of erythrocyte storage and oxyhemoglobin affinity changes on cardiac function

1985 ◽  
Vol 248 (4) ◽  
pp. H508-H515 ◽  
Author(s):  
C. S. Apstein ◽  
R. C. Dennis ◽  
L. Briggs ◽  
W. M. Vogel ◽  
J. Frazer ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Coronary Flow ◽  
Myocardial Oxygen Consumption ◽  
Myocardial Function ◽  
Contractile Function ◽  
Storage Conditions ◽  
Tissue Oxygen ◽  
Biochemical Treatment ◽  
Stress States ◽  
Stored Blood

Storage of blood can depress erythrocyte 2,3-diphosphoglycerate (DPG) levels and thereby increase oxyhemoglobin affinity and potentially decrease capillary-to-tissue oxygen transport. We measured myocardial function and metabolism in isolated rabbit hearts with fixed coronary flow under basal conditions and during isoproterenol stress at 37 and 30 degrees C, comparing high and low oxyhemoglobin affinity (OHA) erythrocytes. The high OHA state resulted from standard storage conditions, which caused depressed values of DPG and P50 (the oxygen tension at which hemoglobin is 50% saturated). The low OHA erythrocytes were initially stored and then underwent biochemical treatment to restore the DPG and P50 values to normal. The low OHA cells released more oxygen, and myocardial oxygen consumption and contractile function were increased relative to the high OHA cells during both the basal and stress states at both 37 and 30 degrees C. These observations may be relevant for patients with limited coronary flow when such patients receive large transfusions of stored blood.

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