The effect of chronic L-arginine administration on vascular recovery following cold cardioplegic arrest in rats.
OBJECTIVE
Acute administration of L-arginine (LA), the physiological substrate of nitric oxide, has been used as a strategy for myocardial protection during ischemia-reperfusion. The aim of this study was to assess the effects of chronic oral LA administration on vascular functions and morphology after prolonged cold cardioplegic arrest.


METHODS
Adult male Sprague-Dawley rats (600-650 g) were divided into control and LA groups, which received LA (4 mg/ml) for 6 weeks. Two experimental protocols were carried out. (1) Isolated rat heart perfusion was performed and hearts were subjected to ischemia for 4 h at 4 degrees C using cold crystalloid cardioplegia (n=8 in LA, n=7 in control). Endothelial and vascular smooth muscle functions were assessed through observations of pre- and post-ischemic coronary flow response to 5-hydroxytryptamine (5-HT) and glyceryl trinitrate (GTN) (%5-HT and %GTN, respectively). (2) Semi-quantitative assessment of tissue morphology was conducted after the same ischemia-reperfusion protocol (n=4 in each group).


RESULTS
The LA group showed significantly better recovery (post-/pre-ischemic value) of %5-HT (97.0+/-65.6 versus 21.5+/-25.7%, P=0.015) and %GTN (124.5+/-117.6 versus 47.7+/-16.6%, P=0.021). The histological assessment showed no significant differences between the two groups.


CONCLUSIONS
Chronic oral administration of LA significantly ameliorated the postischemic recovery of endothelial and vascular smooth muscle functions after cold cardioplegic arrest in rats.
Nakamura
Koki
K
National Heart and Lung Institute Heart Science Centre, Harefield Hospital, Harefield, Middlesex UB9 6JH, UK.
Schmidt
Ilona
I
Gray
Caroline C
CC
Dewar
Ann
A
Rothery
Steve
S
Severs
Nicholas J
NJ
Yacoub
Magdi H
MH
Amrani
Mohamed
M
D000284:Administration, Oral; D000818:Animals; D001120:Arginine / Q000008:administration & dosage* / Q000097:blood; D003080:Cold Temperature; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D006324:Heart Arrest, Induced; D007036:Hypothermia, Induced; D008297:Male; D023421:Models, Animal; D008955:Models, Cardiovascular; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000097:blood; D005996:Nitroglycerin / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D013997:Time Factors; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000494:pharmacology
D016166:Free Radical Scavengers; D014665:Vasodilator Agents; D009569:Nitric Oxide; D012701:Serotonin; D001120:Arginine; D005996:Nitroglycerin