A method for the evaluation of calcitonin secretion using the isolated perfused porcine thyroid

A method for the in vitro perfusion of isolated porcine thyroid glands was developed. The intact glands were placed in a chamber and perfused at a rate of 2.5 ml/min with an oxygenated Tris-balanced salt solution maintained at 37 degrees C. Perfusate fractions were collected at 5-min intervals and analyzed for immunoreactive porcine calcitonin (CT). Calcitonin secretion increased in a dose-related manner with the level of calcium ion (2.5-6.25 mM) in the perfusion solution to a level of 7.5-fold greater than baseline levels. Other established CT secretagogues, such as theophylline (5 mM) and pentagastrin (4 microM), were found to stimulate calcitonin secretion. The CT secretory responsiveness of this system appears to mimic, both quantitatively and qualitatively, the secretory pattern observed in vivo in the pig. Therefore, this perfusion method should provide a valid in vitro model for the study of the process of CT secretion in the mammalian thyroid.