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Exogenous nitric oxide requires an endothelial glycocalyx to prevent postischemic coronary vascular leak in guinea pig hearts.

Bruegger D, Rehm M, Jacob M, Chappell D, Stoeckelhuber M, Welsch U, Conzen P, Becker BF - Crit Care (2008)

Bottom Line: Tissue edema was significantly attenuated in this group.Acute postischemic myocardial release of lactate was comparable in the four groups, whereas release of adenine nucleotide catabolites was reduced 42% by NO.The coronary venous level of uric acid, a potent antioxidant and scavenger of peroxynitrite, paradoxically decreased during postischemic infusion of NO.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clinic of Anesthesiology, Ludwig-Maximilians-University, Marchioninistrasse 15, 81377 Munich, Germany. dirk.bruegger@med.uni-muenchen.de

ABSTRACT

Introduction: Postischemic injury to the coronary vascular endothelium, in particular to the endothelial glycocalyx, may provoke fluid extravasation. Shedding of the glycocalyx is triggered by redox stress encountered during reperfusion and should be alleviated by the radical scavenger nitric oxide (NO). The objective of this study was to investigate the effect of exogenous administration of NO during reperfusion on both coronary endothelial glycocalyx and vascular integrity.

Methods: Isolated guinea pig hearts were subjected to 15 minutes of warm global ischemia followed by 20 minutes of reperfusion in the absence (Control group) and presence (NO group) of 4 microM NO. In further experiments, the endothelial glycocalyx was enzymatically degraded by means of heparinase followed by reperfusion without (HEP group) and with NO (HEP+NO group).

Results: Ischemia and reperfusion severely damaged the endothelial glycocalyx. Shedding of heparan sulfate and damage assessed by electron microscopy were less in the presence of NO. Compared with baseline, coronary fluid extravasation increased after ischemia in the Control, HEP, and HEP+NO groups but remained almost unchanged in the NO group. Tissue edema was significantly attenuated in this group. Coronary vascular resistance rose by 25% to 30% during reperfusion, but not when NO was applied, irrespective of the state of the glycocalyx. Acute postischemic myocardial release of lactate was comparable in the four groups, whereas release of adenine nucleotide catabolites was reduced 42% by NO. The coronary venous level of uric acid, a potent antioxidant and scavenger of peroxynitrite, paradoxically decreased during postischemic infusion of NO.

Conclusion: The cardioprotective effect of NO in postischemic reperfusion includes prevention of coronary vascular leak and interstitial edema and a tendency to forestall both no-reflow and degradation of the endothelial glycocalyx.

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Experimental protocols. After heart preparation and an equilibration period of 15 minutes, hearts were subjected to 15 minutes of global normothermic ischemia followed by 20 minutes of reperfusion. Hearts were reperfused in the absence (Control group) and presence (NO group) of 4 μM nitric oxide. In two further series, the glycocalyx was enzymatically degraded by heparinase, applied into the coronary system in the course of ischemia, followed again by reperfusion in the absence (HEP group) and presence (HEP+NO group) of 4 μM NO. Transudate and coronary effluent were quantified at baseline (B) (just before ischemia) and at 1, 2, 3, 4, 5, 8, 15, and 20 minutes of reperfusion. HEP, heparinase.
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Figure 1: Experimental protocols. After heart preparation and an equilibration period of 15 minutes, hearts were subjected to 15 minutes of global normothermic ischemia followed by 20 minutes of reperfusion. Hearts were reperfused in the absence (Control group) and presence (NO group) of 4 μM nitric oxide. In two further series, the glycocalyx was enzymatically degraded by heparinase, applied into the coronary system in the course of ischemia, followed again by reperfusion in the absence (HEP group) and presence (HEP+NO group) of 4 μM NO. Transudate and coronary effluent were quantified at baseline (B) (just before ischemia) and at 1, 2, 3, 4, 5, 8, 15, and 20 minutes of reperfusion. HEP, heparinase.

Mentions: Hearts were randomly assigned among the experimental groups. Figure 1 illustrates the protocols applied to four groups of hearts. The standard condition was that of constant coronary flow perfusion (6.0 mL/minute) at 37°C. After an equilibration period of 15 minutes, hearts were subjected to 15 minutes of global, normothermic, stopped-flow ischemia and then reperfused under the same condition as before ischemia. To maintain the temperature of the preparation during ischemia, hearts were immersed in warm Tyrode's buffer (37°C). Hearts were reperfused in the absence of NO (Figure 1, Control group), in the presence of 4 μM NO (NO group), and after the glycocalyx had been enzymatically degraded by means of heparinase (10 U of enzyme in a volume of 1.5 mL applied into the coronaries in the course of the 15-minute ischemic phase), both without NO (HEP group) or with 4 μM NO (HEP+NO group). Samples of transudate and coronary effluent were taken at baseline and during reperfusion. At the end of each experiment, hearts were removed from the perfusion system and the atria and large vessels cut away. Excess surface and intraventricular fluid was swabbed off and the ventricles weighed at once.


Exogenous nitric oxide requires an endothelial glycocalyx to prevent postischemic coronary vascular leak in guinea pig hearts.

Bruegger D, Rehm M, Jacob M, Chappell D, Stoeckelhuber M, Welsch U, Conzen P, Becker BF - Crit Care (2008)

Experimental protocols. After heart preparation and an equilibration period of 15 minutes, hearts were subjected to 15 minutes of global normothermic ischemia followed by 20 minutes of reperfusion. Hearts were reperfused in the absence (Control group) and presence (NO group) of 4 μM nitric oxide. In two further series, the glycocalyx was enzymatically degraded by heparinase, applied into the coronary system in the course of ischemia, followed again by reperfusion in the absence (HEP group) and presence (HEP+NO group) of 4 μM NO. Transudate and coronary effluent were quantified at baseline (B) (just before ischemia) and at 1, 2, 3, 4, 5, 8, 15, and 20 minutes of reperfusion. HEP, heparinase.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2481466&req=5

Figure 1: Experimental protocols. After heart preparation and an equilibration period of 15 minutes, hearts were subjected to 15 minutes of global normothermic ischemia followed by 20 minutes of reperfusion. Hearts were reperfused in the absence (Control group) and presence (NO group) of 4 μM nitric oxide. In two further series, the glycocalyx was enzymatically degraded by heparinase, applied into the coronary system in the course of ischemia, followed again by reperfusion in the absence (HEP group) and presence (HEP+NO group) of 4 μM NO. Transudate and coronary effluent were quantified at baseline (B) (just before ischemia) and at 1, 2, 3, 4, 5, 8, 15, and 20 minutes of reperfusion. HEP, heparinase.
Mentions: Hearts were randomly assigned among the experimental groups. Figure 1 illustrates the protocols applied to four groups of hearts. The standard condition was that of constant coronary flow perfusion (6.0 mL/minute) at 37°C. After an equilibration period of 15 minutes, hearts were subjected to 15 minutes of global, normothermic, stopped-flow ischemia and then reperfused under the same condition as before ischemia. To maintain the temperature of the preparation during ischemia, hearts were immersed in warm Tyrode's buffer (37°C). Hearts were reperfused in the absence of NO (Figure 1, Control group), in the presence of 4 μM NO (NO group), and after the glycocalyx had been enzymatically degraded by means of heparinase (10 U of enzyme in a volume of 1.5 mL applied into the coronaries in the course of the 15-minute ischemic phase), both without NO (HEP group) or with 4 μM NO (HEP+NO group). Samples of transudate and coronary effluent were taken at baseline and during reperfusion. At the end of each experiment, hearts were removed from the perfusion system and the atria and large vessels cut away. Excess surface and intraventricular fluid was swabbed off and the ventricles weighed at once.

Bottom Line: Tissue edema was significantly attenuated in this group.Acute postischemic myocardial release of lactate was comparable in the four groups, whereas release of adenine nucleotide catabolites was reduced 42% by NO.The coronary venous level of uric acid, a potent antioxidant and scavenger of peroxynitrite, paradoxically decreased during postischemic infusion of NO.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clinic of Anesthesiology, Ludwig-Maximilians-University, Marchioninistrasse 15, 81377 Munich, Germany. dirk.bruegger@med.uni-muenchen.de

ABSTRACT

Introduction: Postischemic injury to the coronary vascular endothelium, in particular to the endothelial glycocalyx, may provoke fluid extravasation. Shedding of the glycocalyx is triggered by redox stress encountered during reperfusion and should be alleviated by the radical scavenger nitric oxide (NO). The objective of this study was to investigate the effect of exogenous administration of NO during reperfusion on both coronary endothelial glycocalyx and vascular integrity.

Methods: Isolated guinea pig hearts were subjected to 15 minutes of warm global ischemia followed by 20 minutes of reperfusion in the absence (Control group) and presence (NO group) of 4 microM NO. In further experiments, the endothelial glycocalyx was enzymatically degraded by means of heparinase followed by reperfusion without (HEP group) and with NO (HEP+NO group).

Results: Ischemia and reperfusion severely damaged the endothelial glycocalyx. Shedding of heparan sulfate and damage assessed by electron microscopy were less in the presence of NO. Compared with baseline, coronary fluid extravasation increased after ischemia in the Control, HEP, and HEP+NO groups but remained almost unchanged in the NO group. Tissue edema was significantly attenuated in this group. Coronary vascular resistance rose by 25% to 30% during reperfusion, but not when NO was applied, irrespective of the state of the glycocalyx. Acute postischemic myocardial release of lactate was comparable in the four groups, whereas release of adenine nucleotide catabolites was reduced 42% by NO. The coronary venous level of uric acid, a potent antioxidant and scavenger of peroxynitrite, paradoxically decreased during postischemic infusion of NO.

Conclusion: The cardioprotective effect of NO in postischemic reperfusion includes prevention of coronary vascular leak and interstitial edema and a tendency to forestall both no-reflow and degradation of the endothelial glycocalyx.

Show MeSH
Related in: MedlinePlus