title: The adenylate cyclase system and calcitonin secretion from perfused dog thyroid lobes.
abstract: The aim of the study was to assess the involvement of the adenylate cyclase system in calcitonin (CT) secretion from thyroidal C-cells. The cAMP analogues Br-cAMP (10(-6) and 10(-4) mol/l) and DB-cAMP (10(-4) mol/l) and the activators of adenylate cyclase cholera toxin (0.1 microgram/ml and 5 micrograms/ml) and forskolin (10(-7) mol/l and 10(-5) mol/l) were infused for 6 min periods in perfused dog thyroid lobes. CT was measured in thyroid effluent by radioimmunoassay. Br-cAMP and cholera toxin did not alter basal CT secretion. DB-cAMP had a minimal stimulatory effect and forskolin 10(-5) mol/l a moderate stimulatory effect. This was much less than the effect of increasing perfusate Ca++ from 1.5 to 2.0 mmol/l. 10(-4) mol/l Br-cAMP increased the response to Ca++ with approximately 50 per cent. These results suggest that the activity of the adenylate cyclase system of the C-cells by itself is of little importance for CT secretion, but that it may have a role as modulator of the response to Ca++.
authors.affiliation: Second University Clinic of Internal Medicine, Aarhus Kommunehospital, Denmark.
authors.forename: P
authors.initials: P
authors.lastname: Laurberg
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002116:Calcitonin / Q000378:metabolism*; D002772:Cholera Toxin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D004285:Dogs; D066298:In Vitro Techniques; D013961:Thyroid Gland / Q000201:enzymology* / Q000378:metabolism
chemical_list: D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D003994:Bucladesine; D002116:Calcitonin; D002772:Cholera Toxin; D000262:Adenylyl Cyclases