AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 5 1092-R1099, Copyright © 1993 by American Physiological Society
Plasticity of autonomic control of emesis in irradiated ferrets
M. T. Makale and G. L. King
Department of Physiology, Armed Forces Radiobiology Research Institute, Bethesda, Maryland 20889-5145.
To investigate the plasticity of the emetic response to irradiation, five
groups of ferrets (with the appropriate controls) had either the vagal or
the splanchnic nerves transected and either were immediately irradiated
under urethan anesthesia or were irradiated in a conscious state at 0.5-4,
4-9, and 24 h and 7 days after nerve transection. All the ferrets used in
this study had the left carotid artery and the right jugular vein
catheterized several hours before irradiation so that blood pressures could
be monitored. In ferrets that were irradiated while anesthetized, bilateral
abdominal vagotomy performed immediately before 6-Gy irradiation prevented
emesis. Acute bilateral abdominal splanchnicectomy markedly reduced emesis
in such cases but had no statistically significant effect in conscious
ferrets. The incidence of emesis in conscious controls laparotomized 0.5-4
h before irradiation was 50% after 2 Gy and 100% after 6 Gy. Intact
conscious controls were tested with 10 Gy only and showed a 100% incidence
of emesis after this dose. Bilateral abdominal vagotomy, performed on
ferrets 4-9 h before 8-Gy irradiation of conscious animals, markedly
reduced the incidence of radiation-induced emesis. When performed 24 h
before irradiation, it abolished emesis. In contrast, vagotomy was
ineffective when performed 7 days before irradiation. The data suggest
that, after 2-8 Gy, the vagi are the major emetic pathway in conscious
ferrets and the splanchnic nerves may, under certain conditions, constitute
second or alternate pathways.
