Positive Health Online

Abstract

NG and colleagues, Department of Medicine and Therapeutics, Leicester Royal Infirmary, UK write that in diabetic nephropathy and hypertension, cardiovascular disease is a major cause of mortality and that low antioxidant levels of nutrients such as vitamin C have been associated with such complications.

Background

Methodology

The authors examined uptake mechanisms for ascorbic acid (AA) and dehydroascorbic acid (DHA) in lymphoblasts from normal control subjects (CON), normoalbuminuric insulin-dependent diabetic (IDDM) patients (DCON), patients with IDDM and nephropathy (DN) and hypertensive patients (HT) using high-performance liquid chromatography (HPLC).

Results

DHA uptake was the major mechanism in all four groups of patients and the maximal uptake rate (Vmax) was significantly lower in the DN cells compared with the CON and CDON cells. DHA Vmax was also lower in the HT group compared to the CON group. There were no significant differences in the Km or passive membrane permeability for DHA or the AA uptake. DHA uptake showed a negative correlation to systolic blood pressure.

Conclusion

These data suggest that impaired DHA uptake may be one component of the phenotype expressed by DN cells which may persist in culture. Impaired DHA uptake in vivo, particularly in the presence of hyperglycaemia, leads to impaired regeneration of AA and the depletion of anti-oxidant defences, exposing these individuals to increased risk of cardiovascular disease.

References

Ng LL et al. Uptake mechanisms for ascorbate and dehydroascorbate in lymphoblasts from diabetic nephropathy and hypertensive patients. Diabetologia 41(4): 435-42. Apr 1998.