The effect of vitamin C and/or warmth on forearm blood flow and vascular resistance in sickle cell anaemia subjects.

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.