Role of atrial natriuretic Peptide in oxytocin induced cardioprotection.
BACKGROUND
The purpose of this study was to determine whether endogenous atrial natriuretic peptide (ANP) contributes to the protective effect of neurohypophysial hormone oxytocin (OT) in heart preconditioning.


METHODS
Sprague-Dawley male rats were subjected to 25 min regional ischaemia and 120 min reperfusion and were divided into eight groups. Oxytocin or an equivalent volume of saline was administrated intraperitoneally, 30 min before ischaemia. The OT receptor antagonist (atosiban), ANP receptor antagonist (anantin) and nitric oxide synthase inhibitor (L-NAME) were injected 10 min before OT. In other groups, atosiban, anantin and L-NAME were only administered 40 min prior to ischaemia.


RESULTS
Compared with the ischaemia/reperfusion group (I/R), alterations in infarct size, biochemical parameters [LDH (lactate dehydrogenase), CK-MB (creatine kinase-MB), MDA (malondialdehyde) plasma levels] and severity of ventricular arrhythmia due to I/R injury were attenuated and VF was abolished by OT treatment. These OT effects were eliminated by OT and ANP receptor blockers and nitric oxide synthase inhibitor, but anantin did not reverse the effect of OT in lipid peroxidation.


CONCLUSIONS
These findings demonstrate an important contributory role of ANP in the OT induced protection in myocardial ischaemia reperfusion. OT also reduced lipid peroxidation with a NO-dependent mechanism.
['Houshmand|Fariba|F|', 'Faghihi|Mahdieh|M|', 'Zahediasl|Saleh|S|']
D000818:Animals D009320:Atrial Natriuretic Factor D002316:Cardiotonic Agents D004791:Enzyme Inhibitors D006727:Hormone Antagonists D015227:Lipid Peroxidation D008297:Male D009203:Myocardial Infarction D015428:Myocardial Reperfusion Injury D019331:NG-Nitroarginine Methyl Ester D010120:Oxytocics D010121:Oxytocin D010456:Peptides, Cyclic D051381:Rats D017207:Rats, Sprague-Dawley D014668:Vasotocin
Atrial natriuretic peptide Oxytocin Preconditioning. Ischaemia reperfusion Oxidative stress