Reduced Fluoride Sensitivity of Liver Cells from Rats Chronically Exposed to Fluoride

Abstract

Absrruct:The fluoride sensitivity, determined as effect on protein synthesis (incorporation of "C-leucine), of liver and kidney cells in suspension culture was explored. The cells were freshly prepared by collagenase perfusion from rats given drinking water with or without addition of 100 p.p.m. (5.26 mM) fluoride for 9-28 weeks. The fluoride sensitivity of the liver cells from rats given fluoridated water for more than 9 weeks was decreased compared to cells from control rats, whereas the fluoride sensitivity of the kidney cells from fluoride exposed and control rats appeared similar. Fluoride resistance (i.e. decreased sensitivity)may thus develop also in cells in vivo. When exposed to 3 mM NaF for 1 hour the intracellular concentration of fluoride in liver cells from fluoride exposed and control animals was similar.

No Effect of Prolonged Fluoride Exposure on Cytochrome P‐450 and Associated Monooxygenases or on the Level of Polyamines in the Rat

“…We have previously reported that longer-term exposure of rats to NaF resulted in decreased fluoride sensitivity (inhibition of the rate of protein synthesis) of the liver cells from such animals (Hongslo et al 1980), probably developed as an adaptive response to the fluoride exposure. In the present study, the plasma GOT of the NaF exposed rats ( 6 7 f 2 0 UI/l, n=10) was not significant different from that of the control rats ( 5 8 f 1 8 Table 1.…”

“…It is unlikely that fluoride itself is a genotoxic carcinogen (IARC 1982), but it cannot be excluded that it may modulate the effect of complete carcinogenic substances. It has been reported that low levels of NaF can accelerate tumour growth (Taylor & Taylor 1965), and exposing rats to fluoride may evoke several biochemical changes in the liver (Shearer 1974;Hongslo et al 1980).…”

“…The purpose of the present study was to investigate whether NaF had any effect on enzymes which metabolize carcinogens. Furthermore, we wanted to study if longer-term administration of NaF to rats, previously reported to decrease the fluoride sensitivity of isolated rat liver cells (Hongslo et al 1980), also could induce changes in the levels of polyamines in the liver. Polyamines are involved in the regulation of cell metabolism and cell division (Alfheim & Hongslo 1980).…”