AJP - Endocrinology and Metabolism, Vol 256, Issue 5 E597-E599, Copyright © 1989 by American Physiological Society
Calcium stimulates the release of calcitonin gene-related peptide from the canine thyroid
B. Ahren, R. Ekman and P. Laurberg
Department of Pharmacology, Lund University, Sweden.
The calcitonin gene in the thyroid parafollicular cells generates two
different mRNAs, which encode for the precursors of calcitonin and
calcitonin gene-related peptide (CGRP). In this study, we investigated
whether these two peptides are released simultaneously in the perfused dog
thyroid. The isolated dog thyroid (n = 10) was once-through perfused with a
Krebs-Ringer bicarbonate buffer. After elevation of the buffer Ca2+
concentration from 1.5 to 2.5 mM, a rapid, marked, and parallel secretion
of both calcitonin and CGRP occurred (P less than 0.001). By stepwise
increase of the buffer Ca2+ concentration, it was found that, although an
elevation from 1.5 to 1.65 mM had no influence on the thyroid output of
calcitonin or CGRP, elevations to 1.75, 2.0, and 2.5 mM of Ca2+ induced
dose-dependent parallel increases in the thyroid output of calcitonin and
CGRP. Furthermore, the stimulation with pentagastrin (100 pM) increased the
thyroid output of both calcitonin and CGRP in parallel. It is concluded
that the normal dog thyroid releases calcitonin and CGRP in parallel on
stimulation with Ca2+ and pentagastrin.
