The influence of food intake and ambient temperature on the rate of thyroxine utilization.

Abstract

SUMMARYYoung growing pigs of both sexes were subjected to changes in (1) energy intake, (2) ambient temperature, and (3) bulk of food. The rate of disappearance of injected 125I-labelled thyroxine from the plasma (K) was measured. An analysis of variance revealed that the effect attributable to changes in the energy content of the food intake was statistically significant (P < 0.01). A change in ambient temperature had no statistically significant effect on K, nor did a change in the bulk of food when energy intake was constant (P > 0.05).

Effects of dietary energy supply on serum thyroxine, tri-iodothyronine and insulin concentrations in young horses

“…Meals containing moderate amounts of carbohydrates (diets A and B) were associated with increases in serum T4 concentrations during the first several hours after meal completion. These observations are consistent with reports that T4 secretion rates and serum T4 concentrations are in¬ creased after the ingestion of meals containing carbo¬ hydrate by pigs (Ingram & Kaciuba-Uscilko, 1977;Ingram & Evans, 1980;Dauncey, Ingram, Macari & Ramsden, 1982), man (Spaulding, Chopra, Sherwin & Lyall, 1976;Danforth, Horton, O'Connell et al 1979) and cattle (Blum, Gingins, Schnyder et al 1979 ;Blum, Thomson & Bickel, 1979e). In addition, thyro¬ trophin (TSH) secretion has been reported to increase after feeding in rats (Hugues, Burger, Grouselle et al 1983) and man (Hugues, Burger, Pekary & Hershman, 1984).…”

The Influence of Energy Intake on the Metabolism of 3,5,3′-Tri-Iodothyronine and 3,3′,5′-Tri-Iodothyronine in Young Pigs

“…The changes seen in the disappearance rate of reverse T3 follow a similar trend to that reported earlier for (Ingram & Kaciuba-Uscilko, 1977), although the rate of disappearance of T4 was more sensitive, since a reduction in food intake from 4% to 2% induced a fall in clearance rate from plasma. This may be because the longer plasma half-life of T4 compared with that of reverse T3 makes any change more easily detectable.…”

“…Labelled T3 and reverse T3 each in a dose of 25 µ were injected via the catheter and washed in by withdrawing and reinjecting blood several times before finally injecting 5 ml 0-9% NaCl solution. This procedure has previously been proved to be satisfactory (Ingram & Kaciuba-Uscilko, 1977). Subsequently 5 ml samples of blood were withdrawn at intervals into heparinized tubes and the plasma separated.…”

Hormonal Responses to High and Low Planes of Nutrition in Weanling Thoroughbreds

“…Although Ingram and Evans (1980) reported no effect of meal consumption on T4 concentrations in young pigs after a 12-h fast, they concluded that any changes in T4 secretion or utilization rates will be highly dependent on the sizes and caloric densities of the meals. Evans and Ingram (1977), Ingram and Kaciuba-Uscilko (1977), Ingram and Evans (1980) and Blum et al, (1980) reported increases in T4 secretion rates in growing pigs after increases in the amount and energy content of meals. Danforth et al (1979) reported a similar finding in humans.…”