17.
A C T I O N S O F
V I T A M I N S A
A N D
C
683
The evidence from cultures of animal material is still less conclusive.
Most of the early work is difficult to evaluate, largely due to the application of a subjective criterion of "growth"—often confused with cell
migration—and the complex media employed. A stimulating effect of
added ASA was found by Chambers and Cameron (1943) on the spreading of epithelial sheets, by Di Fiore and Sacerdote de Lustig (1943),
Sacerdote de Lustig (1944a, b) and Nakano and Sawai (1939) on
various chick and guinea-pig embryonic tissues, and by Vogelaar and
Erlichman (1937) on cultures of Crocker mouse Sarcoma 180. Conversely, Gordonoff and Ludwig (1937), Vollmar (1939) and Hengstmann (1939) found no effect with physiological concentrations. The
latter and Nakano and Sawai (1939) observed inhibition with high doses.
More recently Waymouth (1955) cultivated chick-heart explants in
a synthetic ASA-free medium for as long as 100 days and observed
mitoses for up to 30 days. Some residual ASA was undoubtedly stored
in the explants but it is difficult to believe that it could have lasted so
long. Moreover, the synthetic capacity of chick embryonic heart is
negligible (Fabro and Rinaldini, unpublished), so that it may be concluded that mitoses can occur, in this system, without vitamin C.
Working with freshly isolated myoblasts, I have found no improvement on the rate of proliferation by adding excess ASA to a medium
consisting of embryo extract and serum which produced logarithmic
increase in cell number with a mean generation time of 22 h. Daily
doses of up to 100 /xg/ml without embryo extract, either in 20% serum
or in various synthetic media, did not promote growth or improve
survival. Various authors have found that fibroblastic proliferation,
in vivo or in cultures, is not impaired but may even be accelerated by
ASA deficiency. W e may recall in this context that hexenolactone
(parasorbic acid), included by Smith (1946) among ASA analogues,
has a selective inhibitory effect on mesenchymal cells and fibroblastic
growth (Medawar, Robinson and Robinson, 1943; Hauschka, 1944;
Hauschka, Toennies and Swain, 1945). Baker (1936b) found that exogenous ASA had no effect on the proliferation of monocytes till after
the second week in vitro, "presumably when the cells had depleted their
own reserves". This explanation, however, seems unlikely in view of the
poor stability of the vitamin. Baker herself noted that ASA was completely oxidized in less than 24 h if glutathione was not added to the
cultures.
ASA is an elusive substance with which to work. If added to cultures
in large amounts it can lower the redox potential beyond physiological
limits and have untoward effects on the cells. If added in physiological
concentrations, it soon disappears from the medium by irreversible
oxidation. Abt and von Schuching (1961) found that the half-life of
A C T I O N S O F
V I T A M I N S A
A N D
C
683
The evidence from cultures of animal material is still less conclusive.
Most of the early work is difficult to evaluate, largely due to the application of a subjective criterion of "growth"—often confused with cell
migration—and the complex media employed. A stimulating effect of
added ASA was found by Chambers and Cameron (1943) on the spreading of epithelial sheets, by Di Fiore and Sacerdote de Lustig (1943),
Sacerdote de Lustig (1944a, b) and Nakano and Sawai (1939) on
various chick and guinea-pig embryonic tissues, and by Vogelaar and
Erlichman (1937) on cultures of Crocker mouse Sarcoma 180. Conversely, Gordonoff and Ludwig (1937), Vollmar (1939) and Hengstmann (1939) found no effect with physiological concentrations. The
latter and Nakano and Sawai (1939) observed inhibition with high doses.
More recently Waymouth (1955) cultivated chick-heart explants in
a synthetic ASA-free medium for as long as 100 days and observed
mitoses for up to 30 days. Some residual ASA was undoubtedly stored
in the explants but it is difficult to believe that it could have lasted so
long. Moreover, the synthetic capacity of chick embryonic heart is
negligible (Fabro and Rinaldini, unpublished), so that it may be concluded that mitoses can occur, in this system, without vitamin C.
Working with freshly isolated myoblasts, I have found no improvement on the rate of proliferation by adding excess ASA to a medium
consisting of embryo extract and serum which produced logarithmic
increase in cell number with a mean generation time of 22 h. Daily
doses of up to 100 /xg/ml without embryo extract, either in 20% serum
or in various synthetic media, did not promote growth or improve
survival. Various authors have found that fibroblastic proliferation,
in vivo or in cultures, is not impaired but may even be accelerated by
ASA deficiency. W e may recall in this context that hexenolactone
(parasorbic acid), included by Smith (1946) among ASA analogues,
has a selective inhibitory effect on mesenchymal cells and fibroblastic
growth (Medawar, Robinson and Robinson, 1943; Hauschka, 1944;
Hauschka, Toennies and Swain, 1945). Baker (1936b) found that exogenous ASA had no effect on the proliferation of monocytes till after
the second week in vitro, "presumably when the cells had depleted their
own reserves". This explanation, however, seems unlikely in view of the
poor stability of the vitamin. Baker herself noted that ASA was completely oxidized in less than 24 h if glutathione was not added to the
cultures.
ASA is an elusive substance with which to work. If added to cultures
in large amounts it can lower the redox potential beyond physiological
limits and have untoward effects on the cells. If added in physiological
concentrations, it soon disappears from the medium by irreversible
oxidation. Abt and von Schuching (1961) found that the half-life of