H. Lancero et al., EXPOSURE OF PERIODONTAL-LIGAMENT CELLS TO METHYL MERCAPTAN REDUCES INTRACELLULAR PH AND INHIBITS CELL-MIGRATION, Journal of dental research, 75(12), 1996, pp. 1994-2002
Volatile sulfur compounds such as hydrogen sulfide and methyl mercapta
n have been associated with adult periodontitis as well as with healin
g surgical wounds. To examine the effects of these compounds on the pe
riodontium, we assayed periodontal ligament (PDL) cells for changes in
intracellular pH, total protein, and cell migration following chronic
exposure to CH3SH. Intracellular pH was quantitated by fluorescence m
easurements of cells loaded with BCECF, a pH-sensitive dye. Data show
that 48-hour exposure to mercaptan lowered resting intracellular pH bu
t did not consistently alter activity of the Na/H exchanger. This effe
ct was seen in PDL cells from three different patients. Lowered pH was
accompanied by decreases in both total protein and mature alpha 1 and
alpha 2 chains of type I collagen. Since reductions in intracellular
pH and total protein have been associated with inhibition of cell moti
lity, migration was quantitated by sequential computer imaging, which
measured the increase in size of plated cell circles at different time
s of migration. Incubation of PDL cells in pH 7.4 and 6.6 buffers reve
rsibly altered intracellular pH. Migration was reversibly inhibited in
pH 6.8 buffer. Exposure to CH3SH reduced intracellular pH in pH 7.4 b
uffer and in three independent assays inhibited enlargement of cell ci
rcles in pH 7.4 medium. These effects were therefore not related to al
terations of extracellular pH, which remained at 7.4. The results supp
ort the hypothesis that gases such as methyl mercaptan may play a role
in both surgical wound healing and periodontal disease by adversely a
ffecting cell function and suggest that alterations in intracellular p
H may be part of the mechanism for these changes.