Immunoextracted calcitonin in human gastric secretion

Effect of peripherally and centrally administered calcitonin on gallbladder emptying in dogs

The effect of calcitonin on meal-stimulated gallbladder emptying (GBE) was examined after intravenous (i.v.) and intracerebroventricular (i.c.v.) administration in six mongrel dogs. The gallbladder contraction was surveyed by means of real-time ultrasonography in conscious dogs. Calcitonin given i.v. elicited an immediate and strong inhibition of postprandial GBE-the integrated 0- to 120-min gallbladder response was 118.1 +/- 8.0%.h after placebo, whereas it was 91.8 +/- 2.1%.h, 59.4 +/- 17.9%.h (P < 0.001), and 14.2 +/- 20.5%.h (P < 0.001) after 3.6, 18.0, and 90.0 pmol.kg-1 calcitonin, respectively. After i.c.v. administration (1.8 and 18.0 pmol.kg-1), only the higher calcitonin dose exerted a moderate inhibitory effect on postprandial GBE. The calcitonin doses required to evoke a 50% inhibition of meal-stimulated GBE were 15- to 10-fold lower after i.v. than i.c.v. application. Peripherally given calcitonin brought about a dose-dependent increase in the interdigestive gallbladder volume-the linear regression of the relative gallbladder volume versus calcitonin dose was y = 11.60 [ln(dose + 1)] + 97.02 (r = 0.864, P < 0.001). Intravenous application of calcitonin did not affect caerulein-induced GBE. The results obtained imply that: (i) calcitonin exerts an inhibitory influence on meal-induced GBE and that this effect is more pronounced after i.v. than after i.c.v. administration, and (ii) peripherally given calcitonin does not inhibit caerulein-induced gallbladder contraction in the dog.

Hypoplasia of G cells in long term steroid-treated rats after ultra-high dose of salmon calcitonin

Male young adult Wistar rats were treated parenterally with cortisol and cortisol combined with salmon calcitonin for 28 and 56 days and the stomach was investigated histologically as well as the G cells using immunohistochemistry. After 28 days of cortisol administration desquamation of the superficial layers of gastric mucosa was found and after 56 days ulcer-like changes developed and increased gastrin immunoreactivity was observed. Administration of high doses of salmon calcitonin together with cortisol resulted in a significant hypoplasia of G cells and prevented the pathological changes in the gastric mucosa.

A rapid extraction method for serum calcitonin

A rapid, simple and reliable extraction method for calcitonin from serum has been developed. 2 volumes of acidic ethanol and 1 volume of serum were mixed, centrifuged, and the supernatant was evaporated to dryness. The extracts were reconstituted in assay buffer before radioimmunoassay was performed. Basal concentrations of calcitonin after extraction were 5.4 +/- 3.0 pg-equivalents/ml (mean +/- SD), females, n = 48 and 8.8 +/- 5.5 pg-equivalents/ml, males, n = 42. Calcitonin was detectable in serum from all males and from 90% of the females. The concentrations in males were significantly higher (P less than 0.001). There was a more pronounced calcitonin response in males (n = 12) than in females (n = 12) to a calcium clamp (P less than 0.01). Gel chromatography of serum from patients with medullary thyroid carcinoma on a Sephadex G-75 column and a TSK G 2000 SW column in a fast protein liquid chromatography system, disclosed that the ethanol extraction excluded the high mol mass forms of calcitonin. We propose the acidic ethanol extraction as a convenient method for routine measurements of calcitonin.