This study seeks to examine the effects of vitamin C supplementation or/and warmth on forearm blood flow (FBF) and forearm vascular resistance (FVR) in sickle cell anaemia (SCA) subjects in the steady state. Sixteen (16) SCA subjects of both sexes (mean age, 23.4+/-1.5 yrs.) were studied. Blood pressure (BP, mm Hg) and FBF (ml/min) measurements were made at rest, with warmth stimulation, after vitamin C supplementation for 6 weeks at 300 mg per day and with warmth stimulation after vitamin C supplementation. Warmth stimulation was induced by immersing the left foot in a bowl of water at a temperature of 40 degrees C for 2 minutes. Forearm blood flow (FBF) [corrected] was measured by means of a forearm plethysmograph. Forearm vascular resistance (FVR, arbitrary units) was calculated by dividing mean arterial pressure (MAP) with FBF. Warmth stimulation at 40 C significantly decreased systolic blood pressure (SBP) (p<0.05), diastolic blood pressure (DBP) (p<0.01), MAP (p<0.01) and FVR (p<0.01) but significantly increased FBF (p<0.01). Vitamin C supplementation also significantly reduced SBP (p<0.001), DBP (p<0.01), MAP (p<0.01) and FVR (p<0.05) but significantly increased FBF (p<0.01). After vitamin C supplementation, warmth stimulation potentiated the reduction in SBP (p<0.001), DBP (p<0.01), FVR (p<0.01) and increase in FBF (p<0.01). In conclusion, warmth stimulation at 40 [corrected] degrees C or vitamin C supplementation caused a decrease in arterial blood pressure, forearm vascular resistance and increase in forearm blood flow in sickle cell anaemia subjects. Pretreatment with vitamin C enhanced the vasodilator effect of warmth.

This study seeks to examine the effects of vitamin C supplementation or/and warmth on forearm blood flow (FBF) and forearm vascular resistance (FVR) in sickle cell anaemia (SCA) subjects in the steady state. Sixteen (16) SCA subjects of both sexes (mean age, 23.4+/-1.5 yrs.) were studied. Blood pressure (BP, mm Hg) and FBF (ml/min) measurements were made at rest, with warmth stimulation, after vitamin C supplementation for 6 weeks at 300 mg per day and with warmth stimulation after vitamin C supplementation. Warmth stimulation was induced by immersing the left foot in a bowl of water at a temperature of 40 degrees C for 2 minutes. Forearm blood flow (FBF) [corrected] was measured by means of a forearm plethysmograph. Forearm vascular resistance (FVR, arbitrary units) was calculated by dividing mean arterial pressure (MAP) with FBF. Warmth stimulation at 40 C significantly decreased systolic blood pressure (SBP) (p<0.05), diastolic blood pressure (DBP) (p<0.01), MAP (p<0.01) and FVR (p<0.01) but significantly increased FBF (p<0.01). Vitamin C supplementation also significantly reduced SBP (p<0.001), DBP (p<0.01), MAP (p<0.01) and FVR (p<0.05) but significantly increased FBF (p<0.01). After vitamin C supplementation, warmth stimulation potentiated the reduction in SBP (p<0.001), DBP (p<0.01), FVR (p<0.01) and increase in FBF (p<0.01). In conclusion, warmth stimulation at 40 [corrected] degrees C or vitamin C supplementation caused a decrease in arterial blood pressure, forearm vascular resistance and increase in forearm blood flow in sickle cell anaemia subjects. Pretreatment with vitamin C enhanced the vasodilator effect of warmth.

The effects of warmth stimulation and/or supplementation with vitamin E (300 mg/day for 6 weeks) on forearm blood flow (FBF) and forearm vascular resistance (FVR) were measured in 8 sickle cell anaemia (SCA) (mean age = 22.8 + 0.8 years) and 11 non sickle cell anaemia (NSCA) subjects (mean age = 23.2 + 1.1 years) of both sexes. Warmth stimulation was induced by immersing the left foot in warm water at 400C for 2 minutes. Forearm blood flow was measured with the venous occlusion plethysmography method. Warmth increased FBF (p<0.01 in each group) and reduced FVR (p<0.05) in NSCA subjects. The change in FBF was greater (p<0.05) in the NSCA subjects than in the SCA subjects. Supplementation with vitamin E reduced systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MAP) (p<0.001 in each case) in the NSCA subjects but had little or no effect on the SCA subjects. Vitamin E increased FBF in NSCA subjects (p<0.05) and SCA subjects (p<0.01) and decreased FVR in both groups (p<0.05 in NSCA and p<0.01 in SCA subjects). The change in FVR seen in the NSCA subjects was less (p<0.01) than the change in SCA subjects. After supplementation with vitamin E, warmth further decreased SBP (p<0.01 in each group) and FVR (p<0.01 in each case) and increased FBF in both groups (p<0.01 respectively). The changes caused by warmth after vitamin E supplementation on the blood pressure parameters, FBF and FVR were similar in the two groups of subjects.