Possible Interaction: Acetylcholine and Arginine

“After four weeks, internal radial artery diameter increased by 8.8 +/- 0.9% after ACh 30 microg/min in L-arg. (”

“Vasodilatation to acetylcholine , 37 microg/min, was significantly enhanced at 60 min (percentage increase in forearm blood flow: placebo, 413 +/- 64%; L-arginine , 587 +/- 94%; p < 0.05), discernible at 120 min (p = 0.058) but no longer apparent at 180 min.”

“Acute intra-arterial administration of L-arginine (10 mg/min) augmented the response to acetylcholine (15 micrograms/min) in both groups before and after supplementation to a similar degree (mean augmentation: 60 +/- 18%, P < 0.01).”

“After 6 months, the coronary blood flow in response to acetylcholine in the subjects who were taking L-arginine increased compared with the placebo group (149 +/- 20% versus 6 +/- 9%, P < 0.05).”

“ L-arginine improves the coronary blood flow response to acetylcholine in patients with normal coronary arteries and hypercholesterolaemia.”

“In adult patients (31 to 45 years), L-arginine still potentiated the vasodilation to acetylcholine , and indomethacin began to show some effect.”

“In normotensive subjects older than 30 years, L-arginine potentiated the response to acetylcholine in parallel with increasing age, whereas indomethacin increased the vasodilation to acetylcholine only in the oldest group (>60 years).”

“In younger hypertensive patients (<30 years), L-arginine but not indomethacin potentiated the response to acetylcholine.”

“In contrast, L-arginine at 10 mg/min significantly (p < 0.01) augmented the forearm blood flow response to acetylcholine (4 to 24 micrograms/min) to a similar extent in the two groups.”

“Taken together, these data indicate that ACh stimulates L-arginine uptake in cultured endothelial cells and in human forearm circulation, indicating the potential for acute modulation of endothelial L-arginine uptake.”

“If their hypothesis is correct, one would expect reduced eNOS activity to have at … on an endothelium-dependent relaxant as on the GTN response, and that incubation with L-arginine would be expected to … in the response to acetylcholine (which was not demonstrated in … study (Munzel et al., 2000)).”

“The facilitatory dose of L-arginine was ineffective in changing the twitch tension evoked by retrograde injection of acetylcholine.”