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Vadstrup
Comparative aspects of iodine conservation in mammals.
Vadstrup S.
Comp Biochem Physiol Comp Physiol. 1993 Sep;106(1):15-7. Review.
"1. Comparative aspects of iodine conservation in mammals were studied on the basis of published data on kidney and thyroid weights and function.
2. Very small mammals possessed an efficient reabsorption of iodide to compensate for the high glomerular filtration rate (GFR).
3. Humans and mammals of a similar and larger size had "lost" the ability to reabsorb iodide efficiently.
4. Very large mammals are protected against renal loss of iodide due to the relatively low GFR.
5. Thyroid weights in relation to body weight were
highest in humans suggesting that humans and other mammals of a
similar size are especially susceptible to iodine deficiency."
Renal iodide clearance in rabbits.
Vadstrup S.
Acta Endocrinol (Copenh). 1989 Aug;121(2):246-50.
[abstract only]
"The purpose of the study was to compare indirect clearance methods based on plasma values and external detection of activity using small skin attached radioactivity detectors with a direct clearance method based on constant infusion and urine collection. The experiments were performed in anesthetized rabbits. The plasma iodide concentration was increased 100 times to prevent thyroid organification of radioactive iodide. [131I]iodide was infused at a constant rate and [125I]iodide was administered iv as a bolus for indirect clearance determination. The ratio between plasma values and external values 125I-activity was constant in all experiments from 15 min after administration of [125I]iodide and throughout the experiment. The results of 7 experiments in 3 rabbits showed a highly significant correlation (r = 0.98) between direct and indirect values within the range of direct clearance values obtained (0.002-0.6 ml.min-1.kg-1. The direct and indirect clearances were measured simultaneously during a 2-h period of steady state. The 95% confidence interval of the mean ratio between direct and indirect clearances was +/- 20% for plasma activity and +/- 26% for externally measured activity. It is concluded that both methods of indirect clearance determination can be applied to rabbits to estimate absolute values of the renal iodide clearance."
A comparison of the effect of TSH, GH and prolactin on the renal iodide excretion in unrestrained rabbits.
Vadstrup S
Acta Endocrinol (Copenh). 1977 Jul;85(3):488-96.
[abstract only]
"The immediate effect of graded iv doses of heterologous TSH, GH and prolactin on the renal iodide excretion was sutdied in unrestrained rabbits with implanted Geiger Muller detectors. Both TSH and GH lowered the fractional excretion rate of iodide. The duration of the effect was significantly correlated to the magnitude of the administered dose. The lowest dose with a significant effect was 10-20 mU TSH and 50 mU GH. Prolactin had no similar effect even in high pharmacological doses. An effect similar to that of small TSH doses was recorded following administration of 20-40 microng TRH iv. The immediate effect of GH on the iodide excretion accords with previous reports about similar effect on sodium excretion and suggests, that the effect of GH and TSH on the iodide excretion is secondary to a general effect on kidney function. The demonstration, that the effect is present in unrestrained animals after administration of physiological doses indicates, that the effect is not only of pharmacological significance, but may also have physiological significance."
The immediate effect of TSH on renal iodide excretion rate in rabbits.
Vadstrup S, Bojsen J.
Acta Endocrinol (Copenh). 1976 Apr;81(4):723-8.
"The renal iodide excretion rate was determined
in unrestrained female rabbits by means of conventional clearance
technique or continuous monitoring of the whole body disappearance of
iv injected 125I-iodide using an implanted Geiger-Muller detector. The
immediate effect of pharmacological doses of bovine TSH was studied by
both methods and a significant decrease in iodide excretion rate was
recorded following the administration of a single TSH dose of 4 IU.
The effect of TSH lasted 3-6 h. Injection of 10-20 mug TRH caused a
transient delay in iodide disappearance (30-50 min) while 2-20 mug
triiodothyronine iv or sc had no immediate effect on the iodide
disappearance."
The diurnal variation in renal iodide excretion rate in rabbits.
Vadstrup S, Bojsen J.
Acta Endocrinol (Copenh). 1976 Apr;81(4):716-22.
[abstract only]
"The
diurnal variation in renal iodide excretion rate was determined in
unrestrained female rabbits by means of either a conventional
clearance technique or a continuous monitoring of the whole body
disappearance of iv injected 125I-iodide using an implanted
Geiger-Muller detector. A distinct diurnal rhythm was detected in the
disappearance rate of 125I-iodide. A slow disappearance rate occurred
from 12 p.m. to 6 a.m. (darkness from 5 p.m. to 5 a.m.). The values of
iodide excretion rate obtained by both methods were consistent like in
humans with an excretion fraction of 0.3 for iodide in rabbits. In
rabbits weighing 3-4 kg the renal iodide excretion rates were 5-7
ml/min during the rapid phase and 3-4 ml/min during the slow phase."