title: [Ischemic preconditioning and exogenous L-arginine reduce infarct size in rabbit heart].
abstract: The effects of NO donor--L-arginine (L-arg) and ischemic preconditioning (IP) on the hemodynamics and myocardial infarct size were examined in the anesthetized rabbit subjected to myocardial ischemia-repefusion to define whether exogenous L-arg could exert a beneficial effect in this pathological model, and whether the L-arg-NO pathway was involved in the cardioprotection provided by IP. The results obtained were as follows: (1) During the course of ischemia (30 min)-reperfusion (180 min), blood pressure, heart rate and myocardial oxygen consumption decreased progressively, and the myocardial infarct size occupied 33.9 +/- 2.4% of the whole left ventricle. (2) The myocardial infarct size could be reduced to 20.1 +/- 2.2% (P < 0.01) by pretreatment with L-arg (300 mg/kg). This myocardial protective effect of L-arg was abolished by NO synthesis inhibitor--Nitro-L-arginine (L-NNA), thereby indicating the involvement of L-arg-NO pathway. (3) IP significantly reduced the infarct size to 21.9 +/- 2.1% (P < 0.01), indicating the prominent cardioprotective effect of such an intervention. Since L-NNA showed no effect on the cardioprotection afforded by IP, it was implied that the L-arg-NO pathway was not involved in the cardioprotective mechanism of IP. (4) Exogenous L-arg might markedly augment cardioprotection provided by IP. The above results strongly suggested that the cardioprotective effect of L-arg on ischemia-reperfused myocardium was mediated by L-arg-NO pathway, which, however, was not involved in the cardioprotection provided by IP.
authors.affiliation: Department of Physiology, Hebei Medical University, Shijiazhuang.
authors.forename: Y F
authors.initials: YF
authors.lastname: Ding
authors.forename: Y L
authors.initials: YL
authors.lastname: Li
authors.forename: S Y
authors.initials: SY
authors.lastname: Ho
mesh_terms: D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology* / Q000517:prevention & control; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D019335:Nitroarginine / Q000494:pharmacology; D011817:Rabbits
chemical_list: D019335:Nitroarginine; D001120:Arginine