Effects of L-arginine on impaired acetylcholine-induced and ischemic vasodilation of the forearm in patients with heart failure.
BACKGROUND
Endothelium-dependent vasodilation in response to acetylcholine (ACh) and ischemic vasodilation during reactive hyperemia are attenuated in the forearm of patients with heart failure (HF). It has been shown that L-arginine augments endothelium-dependent vasodilation in healthy subjects. Thus, the aim of the present study was to determine if L-arginine improves endothelium-dependent and ischemic vasodilation in the forearm in HF.


RESULTS
Forearm blood flow was measured by a strain-gauge plethysmograph in 20 patients with HF and in 24 age-matched control subjects (C). Resting forearm vascular resistance (FVR) was significantly higher in HF than in C (37 +/- 4 versus 22 +/- 2 U, P < .01). Intra-arterial infusions of ACh or sodium nitroprusside (SNP) at graded doses progressively decreased FVR in HF as well as in C. The magnitude of ACh-induced vasodilation was attenuated in HF (P < .01), whereas SNP-induced vasodilation was similar between the two groups. The minimal FVR during reactive hyperemia after 10 minutes of arterial occlusion was significantly higher in HF (n = 12) than in C (n = 12) (3.2 +/- 0.4 versus 2.1 +/- 0.1 U, P < .05). L-Arginine significantly augmented maximal vasodilation evoked with ACh and decreased minimal FVR during reactive hyperemia in HF (P < .01) but not in C. L-Arginine did not affect SNP-induced vasodilation in HF or C.


CONCLUSIONS
Our results suggest that defective endothelial function may contribute to impaired ischemic vasodilator capacity in HF.
Hirooka
Y
Y
Research Institute of Angiocardiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Imaizumi
T
T
Tagawa
T
T
Shiramoto
M
M
Endo
T
T
Ando
S
S
Takeshita
A
A
D000109:Acetylcholine / Q000494:pharmacology; D001120:Arginine / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D010991:Plethysmography; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
D009599:Nitroprusside; D009569:Nitric Oxide; D001120:Arginine; D000109:Acetylcholine