[Effect of sublethal hyperthermia on corneal epithelial proliferation processes in white rats]

A study was made of the effect of sublethal hyperthermia on the mitotic regimen of the corneal epithelium of white rats. The animals were overheated to 41--41.5 degrees C for 1.5 h: in the morning (at 6 o'clock), in the day time (at 11 o'clock) and in the evening (at 17 o'clock). Circadian rhythms were seen in the reaction of the corneal epithelium proliferation to heat exposure. The maximum depression of the mitotic activity was recorded during animals' overheating in the daytime. The 1.7-fold elevation of the mitotic activity was recorded 2 h after morning overheating. No changes were observed after 6 hours. The cell division was found to be suppressed 1.9-fold after 12 hours as compared to control. Sublethal hyperthermia suppressed the number of DNA-synthesizing cells, the label intensity and increased the level of the pathological mitoses.