Vasoactive characteristics of calcitonin in coronary and hepatic circulations

Although parathyroid hormone (PTH) has been shown to possess potent vasodilator and hypotensive properties, little information is available on the cardiovascular effects of the other major calcium-regulating peptide hormone, calcitonin. In the present studies we examined the possibility that calcitonin may be vasoactive in the coronary and hepatic circulations. In anaesthetized open-chest or open-abdomen dogs, salmon calcitonin (sCT) (0.0001-10 IU/kg), PTH-(1-34) or adenosine were injected intra-arterially via the left circumflex or common hepatic artery. Flow probes were placed proximal to the injection sites to determine blood flow rates before and after injections. The results showed that sCT was vasoactive in the dog, eliciting opposite effects on basal flow in the coronary (vasoconstriction) and hepatic (vasodilatation) circulations, but augmenting PTH-induced vasodilatation in both regions.