Effect of Thiocyanate on Iodide Concentrating Systems of the Calf ∗

Abstract

Summary

Effects of thiocyanate on iodide concentration by the calf abomasum, thyroid, and salivary glands were investigated. Five calves were anesthetized 20 hr after intravenous dosing with 200 μCi ¹²⁵I and the left gastroepiploic vein, inferior thyroid vein, and carotid artery cannulated. Saliva flowing from the mouth and blood from each cannula were collected simultaneously at 5-min intervals for 40 min. A second 40-min collection was made after intrajugular injection of 0.33 mM NaSCN/kg of live wt. Thiocyanate increased venous/arterial ¹²⁵I ratios by 22% for the abomasum and 26% for the thyroid, indicating a comparable degree of inhibition of iodide uptake in both concentrating mechanisms. Secretion of ¹²⁵I into mixed saliva was reduced by 29%. In two additional calves, fitted with parotid duct cannulas, secretion of radioiodine into parotid saliva decreased by 75% after thiocyanate administration.