L-arginine: effect on reperfusion injury after heart transplantation.
Global myocardial ischemia and reperfusion injury play a major role in early postoperative myocardial graft dysfunction. The aim of the present study was to investigate the effects of the nitric oxide (NO) precursor L-arginine on myocardial and endothelial function after hypothermic ischemia and reperfusion in a heterotopic rat heart transplantation model. After 1 hour ischemic preservation, reperfusion was started after application of placebo (control, n = 12) or L-arginine (L-Arg 40 mg/kg, n = 12), a substrate of NO synthesis. Myocardial blood flow (MBF) was assessed by the hydrogen clearance method. An implanted balloon was used to obtain pressure-volume relations of the transplanted heart. Left ventricular developed pressure (LVDP), rate of pressure development (dP/dt), end-diastolic pressure (LVEDP), isovolumic relaxation constant (TE), and MBF were measured after 60 minutes and 24 hours of reperfusion. endothelium-dependent vasodilatation in response to acetylcholine (ACh) and endothelium-independent vasodilatation in response to sodium nitroprusside (SNP) were also determined. After 1 hour the MBF was significantly higher in the L-Arg group (3.6 +/- 0.6 vs. 1.9 +/- 0.2 ml/min/g, p < 0.05). The L-Arg group showed better recovery of systolic function and myocardial relaxation (LVDP 106 +/- 6 VS. 70 +/- 7 mmHg, p < 0.05; maximal dP/dt 5145 +/- 498 vs. 3410 +/- 257 mmHg/s, P < 0.05; TE 12.1 +/- 0.9 vs. 16.1 +/- 1.5 ms, p < 0.05, at an intraventricular volume of 80 microliters). LVEDP was similar in the two groups. After 24 hours no difference was found between the groups for basal MBF, LVP dP/dt, TE, LVEDP, or the response of MBF to SNP. However, ACh led to a significantly higher increase in MBF in the L-Arg group (52 +/- 8% vs. 29 +/- 7%, p < 0.05). These results indicate that (1) NO donation improves myocardial and endothelial functional recovery during early reperfusion after heart transplantation; and (2) initial treatment with L-Arg has a persisting beneficial effect against reperfusion-induced graft coronary endothelial dysfunction during late reperfusion.
Department of Cardiac Surgery, University of Heidelberg, Germany.
G
G
Szabó
S
S
Bährle
S
S
Bátkai
N
N
Stumpf
T J
TJ
Dengler
R
R
Zimmermann
C F
CF
Vahl
S
S
Hagl
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects / Q000503:physiopathology; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D016027:Heart Transplantation / Q000009:adverse effects*; D007036:Hypothermia, Induced / Q000009:adverse effects; D009200:Myocardial Contraction / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D012039:Regional Blood Flow / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology; D017725:Ventricular Pressure / Q000187:drug effects
D014665:Vasodilator Agents; D009599:Nitroprusside; D001120:Arginine; D000109:Acetylcholine