Mitotic reduction in rat liver exposed to ultrasound

Abstract

Livers in anesthetized rats were exposed t o 1.90 mHz, 60 mW/cm2 (spatial average) continuous wave ultrasound for five minutes. Subsequent mitotic activity was stimulated by partial hepatectomy. About thirty hours following stimulation (the time of peak mitotic activity in control animals), exposed animals had mean mitotic indices ranging from 20 t o 80% of control values.

Effect of Pulsed Low-Power Ultrasound on Growing Tissues

“…We observed no effect on the mitotic index, an observation which con trasts with that of other investigators [2,3]. However, if our supposition regarding the effect on clonogenicity is correct, no effect on the mitotic index is necessarily expected.…”

“…Evidence suggests that exposure to insonation influences tissue growth in such a way that we thought it possible that tumor growth and transplantability might also be affected [2,3,[5][6][7], Insonation retards the growth of regenerating amphibian tissues [6,7] as well as developing tissues of rats and fruit flies (Drosophila melanogaster) [5] and depresses the mitotic index in both regenerating normal mammalian tissue [2] and neoplastic tissue [3], Inhibition of growth has been reported in a trans plantable tumor of rodents [1] and depression of spermatogenesis of both men and dogs following insonation of testes has also been reported [4].…”

Absence of mitotic reduction in regenerating rat livers exposed to ultrasound

“…Because of this variability control values were determined for each experimental group of animals. Experiments 4 and 5 were similar t o those of Kremkau and Witcofski (9). Rats were sonicated or sham-sonicated under ether anesthesia for a period of five minutes immediately prior to partial hepatectomy.…”

Effect of Pulsed Low-Power Ultrasound on Growing Tissues

“…Those reporting negative results used lesser intensities, closer to those used in clinical diagnostic tests. A reduction in the frequency of mitoses in regenerating liver [7] and of a Wilm's tumor of rats [8] has been reported following insonation at diagnostic frequencies. Sperm produc tion in men and dogs was greatly inhibited, in some cases for periods longer than I year, after single and multiple exposures to ultrasound.…”