X-Message-Number: 24559
Date: Thu, 26 Aug 2004 21:18:54 -0700 (PDT)
From: Doug Skrecky <>
Subject: heat protection by sugars

Int J Hyperthermia. 1985 Oct-Dec;1(4):371-82.
Heat protection by sugars and sugar analogues.
  We have examined the relative ability of 16 sugars and sugar analogues
to reduce cell killing by hyperthermia of 40 min, 45 degrees C. In
general, sugars were added to the culture medium 6 h prior to heating at
a concentration of 100 mM (400 mosmol). The results show that D-hexoses,
L-hexoses, methylated or thiolated sugars and disaccharides significantly
protected cells against thermal damage, increasing survival by factors of
10 to 100. The degree of protection varied for specific sugars and could
not be predicted on the basis of sugar conformation or the number of
hydroxyl groups. Relative heat protection was partially dependent on the
survival assay technique (pre- and post-plating); consistently lower cell
survival was measured when cells were subcultured after hyperthermia,
both in medium-control and sugar-protected cells. However, the time
dependence of heat protection appeared independent of pre- and
post-plating. Cell survival after heating was not increased by two
sugars: (a) D-idose, and (b) 2-deoxy-D-galactose. The latter sugar,
curiously, was also a heat protector but only when cells were trypsinized
after hyperthermia. Both of these sugars were relatively more toxic at 37
degrees C under identical treatment conditions. The lack of protection by
these two sugars is not understood. Another reported non-sugar heat
protector, sodium butyrate, was included as an additional control. Heat
protection by butyrate was not observed in CHO cells. The accumulation of
intracellular free sugar was measured by gas chromatography after
incubating cells for 6 h, 37 degrees C with talose, idose,  L-galactose
or 1-O-methyl-D-glucose. All of these sugars were found in high
concentrations inside of cells. The data are consistent with the
hypothesis that polyhydroxy compounds must accumulate intracellularly for
cellular heat protection.

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