ISSN:
1432-2013
Keywords:
Thyroid Colloid
;
Micropuncture
;
Electrolyte Transport
;
Chloride Concentration
;
Thyroglobulin Concentration
;
Schilddrüsenkolloid
;
Mikropunktion
;
Elektrolyttransport
;
Chloridkonzentration
;
Thyroglobulinkonzentration
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Micropuncture of rat thyroid follicles has been used to study the chloride and protein composition of the colloid. The mean Cl concentration in colloid was 97 mEq/l±20 (S.D.,n=30) and in plasma it was 110±6 mEq/l (n=6). The mean protein concentration in colloid was 25±16 g-% (n=37) relative to a porcine thyroglobulin standard, and in plasma it was 8.3±3.3 g-% relative to a bovine serum albumin standard. From experiments in vitro with solutions of porcine thyroglobulin it was found that a 25 g-% solution of this protein occupied 11.4% of the solution. There was no evidence of selective binding of Na, K or Cl to protein. By applying corrections for protein volume to our previously published data for Na and K concentrations in colloid [16] as well as to our present Cl data we estimated the electrolyte concentrations in the aqueous phase of colloid. From these values we calculated the equilibrium potentials between lumen and interstitium for Na, Cl and K and obtained values of −4.0, −2.9 and −34.0 mV (lumen negative), respectively. From a knowledge of the actual transepithelial potential difference it is possible to conclude that Na and Cl are distributed passively between lumen and interstitium whereas K is actively concentrated in the colloid water. The K concentration was found to increase with increase in the protein concentration of colloid. As our data tended to exclude the possibility of selective protein binding of K, it is concluded that secretion of both K and protein reflects, in some way, the functional state of each acinus.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00586371
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