L-arginine increases nitric oxide and attenuates pressor and heart rate responses to change in posture in sickle cell anemia subjects.

Pressor and heart rate changes following change in posture without or with L-arginine supplementation (1g/day for 6 weeks) were studied in 28 sickle cell anemia (SCA) and 32 non-sickle cell anemia (NSCA) subjects. Change in posture increased HR (p<0.01), RPP (p<0.05) in both groups of subjects, MABP (p<0.05) in SCAS but reduced MABP (p<0.01) in NSCAS and PP (p<0.01) in SCAS. L-Arginine supplementation increased plasma L-Arginine concentration ([R]) in both groups of subjects (p<0.001 in each group) and serum nitric oxide metabolites concentration ([NOx]) (p<0.01 in each group). Change (Δ) [R] correlated positively with Δ [NOx] in both groups (+ 0.7 in each group). L-Arginine supplementation caused greater reduction of MABP (p<0.001) in NSCAS than in SCAS. However, reduction in HR was greater (p<0.001) in SCAS than in NSCAS. After supplementation, MABP and PP responses to change in posture were attenuated in the two groups. However, while HR and RPP responses in SCAS were attenuated, the same responses were enhanced in NSCAS by change in posture after supplementation. In conclusion, study shows that oral, low dose, chronic supplementation with L-arginine increased NO availability and attenuated pressor and heart rate responses to change in posture in sickle cell anemia subjects.