Studies on the uptake of [1- 14C]ascorbic acid and [1- 14C]-dehydroascorbic acid by platelets of guinea pigs

Abstract

Ascorbic acid as well as dehydroascorbic acid were shown to penetrate the platelet membrane in vitro. The percentage uptake by platelets of control guinea pigs (ascorbic acid 0.22 ± 0.014; dehydroascorbic acid 0.54 ± 0.033; p = 0.001) as well as of vitamin C-deficient animals (ascorbic acid 0.40 ± 0.026; dehydroascorbic acid 0.88 ± 0.060; p = 0.001 SEM given) were found to be significantly different. The uptake of ascorbic acid as well as of dehydroascorbic acid were significantly enhanced compared to control animals ( p = 0.001). However, the ratios of uptake of dehydroascorbic acid to ascorbic acid were unaffected (control animals 2.30 ± 0.24; vitamin C-deficient animals (2.30 ± 0.17). The uptake of ascorbic acid was found to be fairly dependent on the concentration and was not influenced by ouabain. On the contrary, the uptake of dehydroascorbic acid did not show a linear dependency on the concentration and was inhibited by 10 −3 M ouabain. These findings suggest an active transport mechanism for the uptake of dehydroascorbic acid whereas in case of ascorbic acid the facilitated diffusion mechanism is discussed. After incubation of platelets of control and vitamin C-deficient animals with [1- 14C]ascorbic acid as well as with [1- 14C]dehydroascorbic acid only [1- 14C] ascorbic acid was detectable in the platelets and only [1- 14C]ascorbic acid was released by the platelets.