Objectives: 

Atrial natriuretic peptide (ANP) decreases hypercontractility which was occur after ischemia of heart. The aim of this study was to determine the hemodynamic effect of ANP in low flow ischemia followed by reperfusion on exercised and non-exercised rat heart.

Materials: 

Male Sprague-Dawley rats were divided into control (C), exercise (E), non-exercise-ANP (NE-ANP) and exercise-ANP (E-ANP) groups. Exercise groups were exposed to running protocol for 5 days. After last bout of exercise, animals were killed. Isolated hearts were perfused with Krebb's Henseleit solution for 15 minutes. Low flow ischemia (60 minutes) and 120-minute-reperfusion were applied in groups. ANP (0.1 &#956;M/L) was added to the perfusion solution in the first 15 minutes of reperfusion period in two (NE-ANP and E-ANP) groups. Left ventricular developed pressure and maximum rate of pressure development (+dP/dT) was recorded during the experiments. Values were analyzed by using Kruskal Wallis test, Friedman test and Dunn's-test and expressed as mean±SEM. The significance level was chosen as p< 0.05.

Results: 

Developed pressure significantly decreased in C (95.13 ± 6.23 vs 4.62 ± 2.10; p<0.01) and E (98.88 ± 11.39 vs 6.07 ± 3.25; p<0.05) groups at the 120 sec of reperfusion. But no significant decrease was obtained in NE-ANP (95.50 ± 4.65 vs 29.56 ± 17.43) and E-ANP (56.36 ± 12.46 vs 22.63 ± 13.05) groups. A significant decrease in +dP/dt values was shown only in C group at 60 min (2965,28 ± 185,18 vs -219,07± 165,74; p<0.01) and 120 min (2965,28 ± 185,18 vs -122,35 ± 173,13; p<0.05) after ischemia however no significant change was shown the other groups.

Conclusions: 

The result of the study indicated that ANP application in reperfusion period may improve the contractility function of both exercised and nonexercised rat hearts.