1
|
Gatzke N, Güc N, Hillmeister P, Dülsner A, Le Noble F, Buschmann EE, Ingwersen M, Bramlage P, Buschmann IR. Cardiovascular drugs attenuated myocardial resistance against ischaemia-induced and reperfusion-induced injury in a rat model of repetitive occlusion. Open Heart 2019; 5:e000889. [PMID: 30613411 PMCID: PMC6307560 DOI: 10.1136/openhrt-2018-000889] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 10/03/2018] [Accepted: 11/12/2018] [Indexed: 12/26/2022] Open
Abstract
Objective We investigated the impact of cardioprotective drugs on ST-elevation, arrhythmias and infarct size in a rat model of repetitive coronary artery occlusion. Methods Seventy Sprague-Dawley rats were randomised to two control and five treatment groups. Placebo was either implantation of a pneumatic occluder onto the left anterior descending coronary artery (LAD) without starting repetitive occlusion (SHAM) or subsequent RO of the LAD over 10 days without medication (ROP). Treatment groups underwent RO and additionally received nitroglycerin (NTG), metoprolol, verapamil (VER), ranolazine (RAN) or candesartan (CAN). Two weeks after the intervention, rats underwent a single, sustained LAD occlusion followed by reperfusion. To evaluate differences in cardiac resistance against myocardial ischaemia and reperfusion injury, cardiac surrogate parameters including maximal ST-elevation, arrhythmias and infarct size were assessed. Results Compared with sham, RO alone and RO plus nitroglycerin were associated with significantly lower maximal ST-elevation and percentage of infarcted myocardium (SHAM 0.12 mV, ROP 0.06 mV (p=0.004), NTG 0.05 mV (p=0.005); SHAM 16.2%, ROP 6.6% (p=0.008), NTG 5.9% (p=0.006). Compared with RO alone, RO plus RAN was accompanied by increased ST-elevation (0.13 mV, p=0.018) and RO plusVER or CAN by more infarcted myocardium (14.2%, p=0.004% and 15.5%, p=0.003, respectively). Rats treated with VER, RAN or CAN tended to severe arrhythmias more frequently than those of the control groups. Conclusions RO led to an increased myocardial resistance against ischaemia and reperfusion injury. Concomitant administration of nitroglycerin did not affect the efficacy of RO. Cardiovascular channel or receptor blockers reduced the efficacy of RO.
Collapse
Affiliation(s)
- Nora Gatzke
- Department for Angiology, Brandenburg Medical School, Campus Brandenburg/Havel, Brandenburg, Germany
- Department of Cardiology, Charité University Hospital, Campus Virchow, Center for Cardiovascular Research (CCR) Charité University Hospital, Berlin, Germany
| | - Nadija Güc
- Department of Cardiology, Charité University Hospital, Campus Virchow, Center for Cardiovascular Research (CCR) Charité University Hospital, Berlin, Germany
| | - Philipp Hillmeister
- Department for Angiology, Brandenburg Medical School, Campus Brandenburg/Havel, Brandenburg, Germany
- Department of Cardiology, Charité University Hospital, Campus Virchow, Center for Cardiovascular Research (CCR) Charité University Hospital, Berlin, Germany
| | - André Dülsner
- Department of Cardiology, Charité University Hospital, Campus Virchow, Center for Cardiovascular Research (CCR) Charité University Hospital, Berlin, Germany
| | - Ferdinand Le Noble
- Department of Cell and Developmental Biology & Institute for Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Eva Elina Buschmann
- Department for Angiology, Brandenburg Medical School, Campus Brandenburg/Havel, Brandenburg, Germany
- Department of Cardiology, Charité University Hospital, Campus Virchow, Center for Cardiovascular Research (CCR) Charité University Hospital, Berlin, Germany
| | - Maja Ingwersen
- Institute for Pharmacology and Preventive Medicine, Cloppenburg, Germany
| | - Peter Bramlage
- Department for Angiology, Brandenburg Medical School, Campus Brandenburg/Havel, Brandenburg, Germany
- Institute for Pharmacology and Preventive Medicine, Cloppenburg, Germany
| | - Ivo R Buschmann
- Department for Angiology, Brandenburg Medical School, Campus Brandenburg/Havel, Brandenburg, Germany
- Department of Cardiology, Charité University Hospital, Campus Virchow, Center for Cardiovascular Research (CCR) Charité University Hospital, Berlin, Germany
| |
Collapse
|
2
|
Stoller M, Seiler C. Pathophysiology of coronary collaterals. Curr Cardiol Rev 2015; 10:38-56. [PMID: 23701025 PMCID: PMC3968593 DOI: 10.2174/1573403x113099990005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 02/28/2013] [Accepted: 04/19/2013] [Indexed: 11/22/2022] Open
Abstract
While the existence of structural adaptation of coronary anastomoses is undisputed, the potential of coronary
collaterals to be capable of functional adaptation has been questioned. For many years, collateral vessels were thought to
be rigid tubes allowing only limited blood flow governed by the pressure gradient across them. This concept was consistent
with the notion that although collaterals could provide adequate blood flow to maintain resting levels, they would be
unable to increase blood flow sufficiently in situations of increased myocardial oxygen demand. However, more recent studies have demonstrated the capability of the collateral circulation to deliver sufficient blood
flow even during exertion or pharmacologic stress. Moreover, it has been shown that increases in collateral flow could be
attributed directly to collateral vasomotion. This review summarizes the pathophysiology of the coronary collateral circulation, ie the functional adapation of coronary
collaterals to acute alterations in the coronary circulation.
Collapse
Affiliation(s)
| | - Christian Seiler
- Department of Cardiology, University Hospital, CH-3010 Bern, Switzerland.
| |
Collapse
|
3
|
Uchida Y, Uchida Y, Maezawa Y, Maezawa Y, Sakurai T, Kanai M, Shirai S, Tabata T. Nitroglycerin-induced heterogeneous subendocardial myocardial blood flow observed by cardioscopy in patients with coronary artery disease. Int Heart J 2011; 52:331-7. [PMID: 22188704 DOI: 10.1536/ihj.52.331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
It is controversial as to whether or not nitroglycerin (NTG) increases subendocardial myocardial blood flow (SMBF), and if it does, whether arterial or venous blood flow is increased in patients with coronary artery disease. This study was performed to examine NTG-induced changes in SMBF.Changes in SMBF induced by NTG (200 µg, i.v.) were examined by cardioscopy in 58 left ventricular wall segments of 58 patients with coronary artery disease. NTG-induced red and purple endocardial colors were defined as increased arterial and venous SMBF, respectively. Endocardial color before NTG administration was classified into brown, light brown, pale and white. Endomyocardial biopsy of the observed portion and (201)Tl scintigraphy were performed in 40 of these patients immediately after cardioscopy and several days after cardioscopy, respectively.Upon administration of NTG, SMBF increased in 48 of 58 wall segments; arterial SMBF in 34 and venous SMBF in 12 wall segments; arterial SMBF in all 24 brown to light brown segments; venous SMBF, arterial SMBF and no change in 12, 10 and 5 of pale segments, respectively; and no change in all 10 white wall segments. (201)Tl-scintigraphy and endomyocardial biopsy revealed that brown, light brown, pale and white endocardial color represented no ischemia, mild ischemia, severe ischemia and fibrosis, respectively.NTG caused an increase in either arterial or venous SMBF depending on control endocardial color, wall motion and severity of coronary stenosis.
Collapse
Affiliation(s)
- Yasuto Uchida
- Department of Cardiology, Toho University Ohmori Hospital, Tokyo, Japan
| | | | | | | | | | | | | | | |
Collapse
|
4
|
Abstract
Exercise is the most important physiological stimulus for increased myocardial oxygen demand. The requirement of exercising muscle for increased blood flow necessitates an increase in cardiac output that results in increases in the three main determinants of myocardial oxygen demand: heart rate, myocardial contractility, and ventricular work. The approximately sixfold increase in oxygen demands of the left ventricle during heavy exercise is met principally by augmenting coronary blood flow (∼5-fold), as hemoglobin concentration and oxygen extraction (which is already 70–80% at rest) increase only modestly in most species. In contrast, in the right ventricle, oxygen extraction is lower at rest and increases substantially during exercise, similar to skeletal muscle, suggesting fundamental differences in blood flow regulation between these two cardiac chambers. The increase in heart rate also increases the relative time spent in systole, thereby increasing the net extravascular compressive forces acting on the microvasculature within the wall of the left ventricle, in particular in its subendocardial layers. Hence, appropriate adjustment of coronary vascular resistance is critical for the cardiac response to exercise. Coronary resistance vessel tone results from the culmination of myriad vasodilator and vasoconstrictors influences, including neurohormones and endothelial and myocardial factors. Unraveling of the integrative mechanisms controlling coronary vasodilation in response to exercise has been difficult, in part due to the redundancies in coronary vasomotor control and differences between animal species. Exercise training is associated with adaptations in the coronary microvasculature including increased arteriolar densities and/or diameters, which provide a morphometric basis for the observed increase in peak coronary blood flow rates in exercise-trained animals. In larger animals trained by treadmill exercise, the formation of new capillaries maintains capillary density at a level commensurate with the degree of exercise-induced physiological myocardial hypertrophy. Nevertheless, training alters the distribution of coronary vascular resistance so that more capillaries are recruited, resulting in an increase in the permeability-surface area product without a change in capillary numerical density. Maintenance of α- and ß-adrenergic tone in the presence of lower circulating catecholamine levels appears to be due to increased receptor responsiveness to adrenergic stimulation. Exercise training also alters local control of coronary resistance vessels. Thus arterioles exhibit increased myogenic tone, likely due to a calcium-dependent protein kinase C signaling-mediated alteration in voltage-gated calcium channel activity in response to stretch. Conversely, training augments endothelium-dependent vasodilation throughout the coronary microcirculation. This enhanced responsiveness appears to result principally from an increased expression of nitric oxide (NO) synthase. Finally, physical conditioning decreases extravascular compressive forces at rest and at comparable levels of exercise, mainly because of a decrease in heart rate. Impedance to coronary inflow due to an epicardial coronary artery stenosis results in marked redistribution of myocardial blood flow during exercise away from the subendocardium towards the subepicardium. However, in contrast to the traditional view that myocardial ischemia causes maximal microvascular dilation, more recent studies have shown that the coronary microvessels retain some degree of vasodilator reserve during exercise-induced ischemia and remain responsive to vasoconstrictor stimuli. These observations have required reassessment of the principal sites of resistance to blood flow in the microcirculation. A significant fraction of resistance is located in small arteries that are outside the metabolic control of the myocardium but are sensitive to shear and nitrovasodilators. The coronary collateral system embodies a dynamic network of interarterial vessels that can undergo both long- and short-term adjustments that can modulate blood flow to the dependent myocardium. Long-term adjustments including recruitment and growth of collateral vessels in response to arterial occlusion are time dependent and determine the maximum blood flow rates available to the collateral-dependent vascular bed during exercise. Rapid short-term adjustments result from active vasomotor activity of the collateral vessels. Mature coronary collateral vessels are responsive to vasodilators such as nitroglycerin and atrial natriuretic peptide, and to vasoconstrictors such as vasopressin, angiotensin II, and the platelet products serotonin and thromboxane A2. During exercise, ß-adrenergic activity and endothelium-derived NO and prostanoids exert vasodilator influences on coronary collateral vessels. Importantly, alterations in collateral vasomotor tone, e.g., by exogenous vasopressin, inhibition of endogenous NO or prostanoid production, or increasing local adenosine production can modify collateral conductance, thereby influencing the blood supply to the dependent myocardium. In addition, vasomotor activity in the resistance vessels of the collateral perfused vascular bed can influence the volume and distribution of blood flow within the collateral zone. Finally, there is evidence that vasomotor control of resistance vessels in the normally perfused regions of collateralized hearts is altered, indicating that the vascular adaptations in hearts with a flow-limiting coronary obstruction occur at a global as well as a regional level. Exercise training does not stimulate growth of coronary collateral vessels in the normal heart. However, if exercise produces ischemia, which would be absent or minimal under resting conditions, there is evidence that collateral growth can be enhanced. In addition to ischemia, the pressure gradient between vascular beds, which is a determinant of the flow rate and therefore the shear stress on the collateral vessel endothelium, may also be important in stimulating growth of collateral vessels.
Collapse
|
5
|
Abstract
Since its discovery over 20 years ago as an intercellular messenger, nitric oxide (NO), has been extensively studied with regard to its involvement in the control of the circulation and, more recently, in the prevention of atherosclerosis. The importance of NO in coronary blood flow control has also been recognized. NO-independent vasodilation causes increased shear stress within the blood vessel which, in turn, stimulates endothelial NO synthase activation, NO release and prolongation of vasodilation. Reactive hyperemia, myogenic vasodilation and vasodilator effects of acetylcholine and bradykinin are all mediated by NO. Ischemic preconditioning, which protects the myocardium from cellular damage and arrhythmias, is itself linked with NO and both the first and second windows of protection may be due to NO release. Exercise increases NO synthesis via increases in shear stress and pulse pressure and so it is likely that NO is an important blood flow regulatory mechanism in exercise. This phenomenon may account for the beneficial effects of exercise seen in atherosclerotic individuals. Whilst NO plays a protective role in preventing atherosclerosis via superoxide anion scavenging, risk factors such as hypercholesterolemia reduce NO release leading the way for endothelial dysfunction and atherosclerotic lesions. Exercise reverses this process by stimulating NO synthesis and release. Other factors impacting on the activity of NO include estrogens, endothelins, adrenomedullin and adenosine, the last appearing to be a compensatory pathway for coronary control in the presence of NO inhibition. These studies reinforce the pivotal role played by the substance in the control of coronary circulation.
Collapse
Affiliation(s)
- D Gattullo
- Dipartimento di Scienze Cliniche e Biologische, Università di Torino, Ospedale S. Luigi, Orbassano, Italy
| | | | | | | |
Collapse
|
6
|
Klassen CL, Traverse JH, Bache RJ. Nitroglycerin dilates coronary collateral vessels during exercise after blockade of endogenous NO production. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H918-23. [PMID: 10484411 DOI: 10.1152/ajpheart.1999.277.3.h918] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In a previous study nitroglycerin failed to dilate coronary collateral vessels during exercise. This study tested the hypothesis that failure of nitroglycerin to increase collateral flow occurred because endogenous nitric oxide (NO) had activated the guanylate cyclase vasodilator pathway so that additional NO from nitroglycerin could have no additional effect. Six dogs were collateralized using intermittent 2-min occlusions of the left anterior descending coronary artery followed by permanent occlusion. One week after permanent coronary occlusion, dogs were exercised on a treadmill (heart rate 202 +/- 5 beats/min), while blood flow was measured with radioactive microspheres. Blood flow to the collateral zone during control exercise was 1.90 +/- 0.11 ml. min(-1). g(-1) compared with 2.28 +/- 0.15 ml. min(-1). g(-1) in the normal zone (P < 0.05); systolic wall thickening was 23 +/- 3% in the collateral zone compared with 27 +/- 2% in the normal zone. When N(G)-nitro-L-arginine (L-NNA; 20 mg/kg iv) was administered to block NO production, collateral zone flow during exercise decreased to 1. 43 +/- 0.20 ml. min(-1). g(-1) (P < 0.05), and systolic wall thickening decreased to 12 +/- 4% (P < 0.05). A subsequent infusion of nitroglycerin (2 microg. kg(-1). min(-1) iv) increased collateral zone blood flow to 1.65 +/- 0.16 ml. min(-1). g(-1) (P < 0.05) and increased systolic wall thickening to 22 +/- 5% (P < 0.05). These findings demonstrate that endogenous NO contributes to collateral zone blood flow during exercise. If endogenous NO synthesis is blocked, then nitroglycerin is effective in improving collateral zone blood flow and contractile function during exercise.
Collapse
Affiliation(s)
- C L Klassen
- Division of Cardiology, Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
| | | | | |
Collapse
|