Effects of n-acetylcysteine on ischemic preconditioning: study in isolated rat hearts.
OBJECTIVE
The aim of this study is to assess if N-Acetylcysteine (NAC) changes the Ischemic Preconditioning (IP) in isolated rat hearts using only one cycle of IP.


METHODS
Heart Rate (HR), Coronary Flow (CF) and Myocardial Contractility (dP/dt) were registered in 30 Wistar rat's hearts. After anesthesia the hearts were removed and perfused with Krebes-Hensleit equilibrated solution with 95% of O2 and 5% of CO2 according Langendorff's method. GI: Control (n=6); GII: 20 min. ischemia (n=6); GIII: IP (n=6); GIV 50 microg/ml/min NAC before IP (n =6); GV: 100 microg/ ml/min NAC before IP (n=6). Parameters were measured after 15 min. of stabilization (T 0) and T3, T5, T10, T15, T20, T25 and T30 min. after reperfusion. Statistical significance was considered when P<0.05.


RESULTS
There were changes on HR comparing GI with GII at T20 and T25 and comparing GI with GIII, GIV with GV at T10 and T20 (P<0.05). CF was different comparing GI with GII at T3 and T5, GI with GIV at T10 and GI with GV at T10 and T25 (P<0.05). Myocardial Contractility was similar comparing GIII with GI and GV. GIII had higher dP/dt than GIV but without statistical difference (P>0.05). dP/dt was higher in GV than GIV but with statistically significant difference only at T30.


CONCLUSIONS
dP/dt was better in preconditioned hearts and was changed if using NAC in GIV. The use of NAC didn't change the effects of preconditioning on myocardial contractility in GV.
Oliveira
Denoel Marcelino de
DM
São Francisco de Assis Cardiovascular Foundation/ServCor - Belo Horizonte, MG, Brasil.
Gomes
Eros Silva
ES
Mussivand
Tofy
T
Fiorelli
Alfredo Inácio
AI
Gomes
Otoni Moreira
OM
D000111:Acetylcysteine / Q000008:administration & dosage*; D000704:Analysis of Variance; D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects*; D016166:Free Radical Scavengers / Q000008:administration & dosage*; D006339:Heart Rate / Q000187:drug effects*; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D023421:Models, Animal; D009200:Myocardial Contraction / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D016166:Free Radical Scavengers; D000111:Acetylcysteine