Effects of ischemic postconditioning on left ventricular function of isolated rat hearts.
OBJECTIVE
To assess the effects of ischemic postconditioning on left ventricular function in isolated rat hearts.


METHODS
Twenty-four Wistar rats were used. These hearts underwent perfusion by modified LANGERDORFF method and distributed into three groups: GI--control (n=8); GII--three cycles of postconditioning of 10/10s (n=8); GIII three cycles of postconditioning of 30/30s (n=8). After a 15 min stabilization period, all hearts underwent 20 min of global ischemia following 20 min of reperfusion. In the times 0 (control), 5, 10, 15 and 20 min of reperfusion, the heart rate (HR), the coronary flow (CoF), the systolic pressure, the (+dP/dt max) contractility and (-dP/dt max) velocity of relaxation were measured. Data were analyzed by ANOVA method followed by Tukey's test for differences between groups and P < 0.05 was considered significant.


RESULTS
The HR (bpm) decreased in all groups after 20 min of reperfusion without statistical differences among them (GI 232.5+36.8; GII 241.8+46.7; GIII 249.4+40.4;P>0.05). The same occurred with the systolic pressure (mmHg) (GI 132.6+49.3; GII 140.8+43.1; GIII 112.6+33.2; P>0.05), coronary blood flow (GI 18.5+4.6; GII 21.4+4.4; GIII 22.1+9.0; P>0.05) and -dP/dt max (mmHg) (GI 1490.6+512.0; GII 1770.4+406.6; GIII 1399.1+327.4; P>0.05). The +dP/dt max (mmHg) decreased significantly in all groups except in group II (GI 1409.0+415.2, GII 1917.3+403.1, GIII 1344.8+355.8) (GII vs GI, P= 0.04; GII vs GIII, P= 0.02).


CONCLUSIONS
The ischemic postconditioning by three cycles of reperfusion/ischemia of 10/10s demonstrated to be effective for preservation of the myocardial contractility in isolated rat hearts which had undergone 20 min of ischemia.
Pinheiro
Bruno Botelho
BB
São Francisco de Assis Cardiovascular Foundation - ServCor Hospital, Belo Horizonte, MG, Brasil. bruno.pinheiro@sbccv.org.br
Fiorelli
Alfredo Inácio
AI
Gomes
Otoni Moreira
OM
D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D003326:Coronary Circulation / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D008297:Male; D023421:Models, Animal; D009200:Myocardial Contraction / Q000502:physiology*; D015425:Myocardial Reperfusion / Q000379:methods*; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D051381:Rats; D011919:Rats, Inbred Strains; D017208:Rats, Wistar; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology*