Effect of controlled coronary occlusion on collateral circulation in conscious dogs

Ec, Elliot; Cm, Bloor; El, Jones; Wj, Mitchell; Grobbee, D. E.

doi:10.1152/ajplegacy.1971.220.4.857

Cited by 42 publications

(8 citation statements)

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“…We previously published coronary angiograms that document that the occluded LCX artery in our model is completely occluded and dependent on collateral vessels for its blood supply (49). Previous studies also documented that blood flow to the chronically occluded main artery is maintained via collateral circulation to this vessel (10,39,40); thus we refer to the LCX as a collateral-dependent artery.…”

Section: Methodsmentioning

confidence: 89%

Exercise training enhances multiple mechanisms of relaxation in coronary arteries from ischemic hearts

Deer

Heaps

2013

American Journal of Physiology-Heart and Circulatory Physiology

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Deer RR, Heaps CL. Exercise training enhances multiple mechanisms of relaxation in coronary arteries from ischemic hearts. Am J Physiol Heart Circ Physiol 305: H1321-H1331, 2013. First published August 30, 2013; doi:10.1152/ajpheart.00531.2013.-Exercise training of coronary artery disease patients is of considerable interest, since it has been shown to improve vascular function and, thereby, enhance blood flow into compromised myocardial regions. However, the mechanisms underlying exercise-induced improvements in vascular function have not been fully elucidated. We tested the hypothesis that exercise training increases the contribution of multiple mediators to endothelium-dependent relaxation of coronary arteries in the underlying setting of chronic coronary artery occlusion. To induce gradual occlusion, an ameroid constrictor was placed around the proximal left circumflex coronary artery in Yucatan miniature swine. At 8 wk postoperatively, pigs were randomly assigned to sedentary or exercise (treadmill, 5 days/wk) regimens for 14 wk. Exercise training significantly enhanced the contribution of nitric oxide, prostanoids, and large-conductance Ca 2ϩ -dependent K ϩ (BKCa) channels to endothelium-dependent, bradykinin-mediated relaxation in nonoccluded and collateral-dependent arteries. Combined nitric oxide synthase, prostanoid, and BK Ca channel inhibition ablated the enhanced relaxation associated with exercise training. Exercise training significantly increased nitric oxide levels in response to bradykinin in endothelial cells isolated from nonoccluded and collateral-dependent arteries. Bradykinin treatment significantly increased PGI 2 levels in all artery treatment groups and tended to be further enhanced after nitric oxide synthase inhibition in exercise-trained pigs. No differences were found in whole cell BK Ca channel currents, BKCa channel protein levels, or arterial cyclic nucleotide levels. Although redundant, upregulation of parallel vasodilator pathways appears to contribute to enhanced endothelium-dependent relaxation, potentially providing a more refined control of blood flow after exercise training. exercise; endothelium; chronic coronary artery occlusion THE ENDOTHELIUM PLAYS AN IMPORTANT role in mediating vascular tone. In response to mechanical stimuli (shear stress and pulsatile pressure) or vasoactive agonists (bradykinin and acetylcholine), endothelium-dependent relaxation occurs through the release of mediators such as nitric oxide and PGI 2 , which affect the adjacent vascular smooth muscle in a paracrine manner. In addition, a third endothelium-derived factor [endothelium-derived hyperpolarizing factor (EDHF)] relaxes vascular smooth muscle by causing hyperpolarization of the underlying smooth muscle cells. While a single EDHF has not been elucidated, numerous candidate mechanisms or pathways have been proposed. Large-conductance Ca 2ϩ -dependent K ϩ (BK Ca ) channels are a common downstream effector for several of these potential EDHFs (2, 27), as well as for nitric oxide (29) and PGI 2 ...

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Section: Methodsmentioning

confidence: 89%

Exercise training enhances multiple mechanisms of relaxation in coronary arteries from ischemic hearts

Deer

Heaps

2013

American Journal of Physiology-Heart and Circulatory Physiology

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“…8 (14,21,(23)(24)(25)(26), radioisotopic determination of collateral flow (15,23,24,(27)(28)(29)(30), and microsphere determination of flow distribution (31 (5), and therefore the special conditions of our protocol must not be overlooked. Collateral vessels in the dog heart are often epicardial, whereas these vessels tend to be intramural in man (38 (18).…”

Section: Resultsmentioning

confidence: 99%

The Effects of Nitroglycerin on Coronary Collaterals and Myocardial Contractility

Cohen¹,

Downey²,

Sonnenblick³

et al. 1973

J. Clin. Invest.

132

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A B S T R A C T Nitroglycerin (TNG) causes a prolonged dilatation of coronary collaterals. To demonstrate a functional significance of this dilatation we measured the effect of TNG on myocardial contractile force in dogs 2j-4 wk after the left anterior descending coronary artery (LAD) had been embolized in closed-chest animals. Development of collaterals was documented by angiography. Via a left thoracotomy the main left coronary artery (LCA) and LAD distal to the embolized plug were cannulated. Coronary flow and perfusion pressure were recorded. Contractile force was measured with gauges sutured to epicardial areas supplied by the left circumflex coronary artery (LCf) and occluded LAD. Coronary perfusion pressure in the LCA was gradually decreased until the contractile force recorded by the LAD gauge diminished while the LCf gauge was unaffected. Under these conditions, with coronary perfusion pressure held constant with the aid of a Starling resistance, TNG (18 ,g) injected into the LCA increased peripheral LAD pressure by 3-12 mm Hg and contractile force in the LAD region by 36% (range 20-90%), returning it to near-normal levels, while having minimal effect in the LCf area. These changes persisted for 5 min. When LCf and LAD areas were both ischemic, intracoronary TNG had minimal effect on peripheral LAD pressure and contractile force. Thus, TNG causes prolonged dilatation of coronary collaterals and presumed increased collateral flow with subsequent enhancement of myocardial contractile force in ischemic areas. This effect is seen only when ischemia is limited to an area supplied by the collaterals. When the whole heart is This study was presented in part at the 22nd Annual

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“…How (13)(14)(15)(16)(17). Sttudies in which gradtual coronary insifficiency was prodtuced by an externally controlled conistrictor cuiff have demonstrated that these preexisting collateral vessels can uindergo suibstantial development in a remarkably short time (18)(19)(20). One metlhod uised to explore the growth potential of intercoroniary collateral channels lhas been the Ameroid constrictor model.…”

Section: Discussionmentioning

confidence: 99%

Effect of exercise on perfusion of collateral-dependent myocardium in dogs with chronic coronary artery occlusion.

Lambert¹,

Hess²,

Bache³

1977

J. Clin. Invest.

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A B S T R A C T Since the ability of mature intercoronary collateral channels to increase myocardial blood flow in response to drug-induced coronary vasodilation has been questioned, the present study was undertaken to evaluate the response of coronary collateral circulation to the stress of exercise. Studies were performed at rest and during two levels of treadmill exercise in six dogs a minimum of 6 mo after placement of an Ameroid constrictor on the left circumflex coronary artery. Regional myocardial blood flow was estimated in normally perfused anterior and predominantly collateral-dependent posterior left ventricular wall with left atrial injections of radionuclide-labeled microspheres 7-10 lOtm in diameter. At rest, heart rate was 87+7 beats/min and mean myocardial blood flow was comparable in control and collateral-dependent regions (0.96+0.13 and 0.97 +0.14 ml/min g, respectively). During exercise, heart rates increased to 180+13 and 228+14 beats/min and myocardial blood flow (MBF) in the anterior control region increased linearly with heart rate (HR), (MBF = 0.133 HR -0.202, r = 0.88). MBF to the posterior collateral-dependent region was similarly augmented during exercise (MBF = 0.140 HR -0.252, r = 0.89), so that the linear correlation between HR and MBF was similar for the control and collateral-

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Effect of controlled coronary occlusion on collateral circulation in conscious dogs

Cited by 42 publications

References 0 publications

Exercise training enhances multiple mechanisms of relaxation in coronary arteries from ischemic hearts

Exercise training enhances multiple mechanisms of relaxation in coronary arteries from ischemic hearts

The Effects of Nitroglycerin on Coronary Collaterals and Myocardial Contractility

Effect of exercise on perfusion of collateral-dependent myocardium in dogs with chronic coronary artery occlusion.

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