Proportions of total blood iodide in the red cells of the rabbit

Summary

1. 321 measurements on the ¹³¹I-iodide content of the erythrocytes were carried out in 27 rabbits under different conditions. 21.48 (±2.49) per cent of the intravascular activity was found to be in the red cells of normal rabbits at a mean haematocrit value of 34.5%. Since the blood volume represents 18 per cent of the ¹³¹I-iodide space in the rabbit, 4.5% of this space can be regarded as part of the intravascular cellular compartment.

2. No significant differences in the intracellular ¹³¹-I-iodide content were found in rabbits on excess iodide and chloride intake and also not in narcosis or after thyroidectomy or plasmapheresis, but there was a marked reduction of radioiodide in the red cells when the rabbit was previously subjected to repeated haemorrhages.

3. The intravascular ¹³¹I-iodide distribution shows only a partial correlation with haematocrit values, the coefficient of this correlation being +0.802.

4. If the distribution of radioiodide between plasma and erythrocytes is calculated on the basis of the plasma/red cell water ratio, in most cases relatively more ¹³¹I-iodide will be found in the plasma than in the erythrocytes. Plasma/red cell ¹³¹I-iodide ratios obtained in normal rabbits averaged 1.18 (±0.095).

5. The results are statistically evaluated and briefly commented on.