Document Detail


The role of NO in ischemia/reperfusion injury in isolated rat heart.
MedLine Citation:
PMID:  16474186     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Nitric oxide (NO) is an important regulator of myocardial function and vascular tone under physiological conditions. However, its role in the pathological situations, such as myocardial ischemia is not unequivocal, and both positive and negative effects have been demonstrated in different experimental settings including human pathology. The aim of the study was to investigate the role of NO in the rat hearts adapted and non-adapted to ischemia. Isolated Langendorff-perfused hearts were subjected to test ischemic (TI) challenge induced by 25 min global ischemia followed by 35 min reperfusion. Short-term adaptation to ischemia (ischemic preconditioning, IP) was evoked by 2 cycles of 5 min ischemia and 5 min reperfusion, before TI. Recovery of function at the end of reperfusion and reperfusion-induced arrhythmias served as the end-points of injury. Coronary flow (CF), left ventricular developed pressure (LVDP), and dP/dt(max) (index of contraction) were measured at the end of stabilization and throughout the remainder of the protocol until the end of reperfusion. The role of NO was investigated by subjecting the hearts to 15 min perfusion with NO synthase (NOS) inhibitor L-NAME (100 mmol/l), prior to sustained ischemia. At the end of reperfusion, LVDP in the controls recovered to 29.0 +/- 3.9 % of baseline value, whereas preconditioned hearts showed a significantly increased recovery (LVDP 66.4 +/- 5.7 %, p < 0.05). Recovery of both CF and dP/dt(max) after TI was also significantly higher in the adapted hearts (101.5 +/- 5.8 % and 83.64 +/- 3.92 % ) as compared with the controls (71.9 +/- 6.3 % and 35.7 +/- 4.87 %, respectively, p < 0.05). NOS inhibition improved contractile recovery in the non-adapted group (LVDP 53.8 +/- 3.1 %; dP/dt(max) 67.5 +/- 5.92 %) and increased CF to 82.4 +/- 5.2 %. In contrast, in the adapted group, it abolished the protective effect of IP (LVDP 31.8 +/- 3.1 %; CF 70.3 +/- 3.4 % and dP/dt(max) 43.25 +/- 2.19 %). Control group exhibited 100 % occurrence of ventricular tachycardia (VT), 57 % incidence of ventricular fibrillation (VF) - 21 % of them was sustained VF (SVF); application of L-NAME attenuated reperfusion arrhythmias (VT 70 %, VF 20 %, SVF 0 %). Adaptation by IP also reduced arrhythmias, however, L-NAME in the preconditioned hearts increased the incidence of arrhythmias (VT 100 %, VF 58 %, SVF 17 %). In conclusion: our results indicate that administration of L-NAME might be cardioprotective in the normal hearts exposed to ischemia/reperfusion (I/R) alone, suggesting that NO contributes to low ischemic tolerance in the non-adapted hearts. On the other hand, blockade of cardioprotective effect of IP by L-NAME points out to a dual role of NO in the heart: a negative role in the non-adapted myocardium subjected to I/R, and a positive one, due to its involvement in the mechanisms of protection triggered by short-term cardiac adaptation by preconditioning.
Authors:
E Andelová; M Barteková; D Pancza; J Styk; T Ravingerová
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  General physiology and biophysics     Volume:  24     ISSN:  0231-5882     ISO Abbreviation:  Gen. Physiol. Biophys.     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2006-02-13     Completed Date:  2006-04-18     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8400604     Medline TA:  Gen Physiol Biophys     Country:  Slovakia    
Other Details:
Languages:  eng     Pagination:  411-26     Citation Subset:  IM    
Affiliation:
Institute for Heart Research, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava 45, Slovakia. usrdende@savba.sk
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MeSH Terms
Descriptor/Qualifier:
Animals
Arrhythmias, Cardiac / etiology,  physiopathology*
Blood Flow Velocity
Blood Pressure
Coronary Circulation
Myocardial Contraction*
NG-Nitroarginine Methyl Ester / pharmacology
Nitric Oxide / metabolism*
Nitric Oxide Synthase / antagonists & inhibitors,  metabolism*
Rats
Rats, Wistar
Reperfusion Injury / complications,  physiopathology*
Ventricular Dysfunction, Left / etiology,  physiopathology*
Chemical
Reg. No./Substance:
10102-43-9/Nitric Oxide; 50903-99-6/NG-Nitroarginine Methyl Ester; EC 1.14.13.39/Nitric Oxide Synthase

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