Moderate level x-ray effect on active transport mechanism in dog intestine.

Abstract

SummaryEarlier reports of this group have described the basic model for analysis of tracer data in the Thiry-Vella preparation using 24Na and 3H as tracers. At that time, it was reported also that the lumen-to-plasma transfer rate of sodium was increased on the third day following 600 r whole-body irradiation (1 MVP). It has since also been possible to demonstrate (1) the active transport of water and (2) increases in the magnitude of active water transport on the second to third day. Active water transport is normally about 20 per cent of the total unidirectional efflux. After irradiation, active water transport is significantly increased by a factor of 1·7. In accordance with a more recent fluid circuit theory of ion accumulation, the increase in active water transport is observed to be accompanied by the increase in sodium efflux. While diffusional and osmotic factors are still operative, conclusions about active water transport were deduced from independent manipulations of osmotic and diffusional dif...