The coronary effects of parathyroid hormone

OBJECTIVE: The aim of the present study was to characterize the role of the ATP-sensitive potassium channels (K(+)(ATP)) in the coronary dilator action of parathyroid hormone (PTH). METHODS: Dose-response curves of intracoronary administrated PTH (0.15-1.33 nmol) were obtained in control phases and during continuous intracoronary administration of the K(+)(ATP) channel-selective antagonist glibenclamide (0.1-1.0 micromol/min) in dogs (n = 13). RESULTS: Increments of integrated coronary conductance (excess coronary conductance) at PTH doses of 0.15 and 1.33 nmol were 1.17 versus 0.03 ml/mm Hg (p < 0.05) and 4.03 versus 0.94 ml/mm Hg (p < 0.05) in the control versus during maximal blockade, respectively. CONCLUSION: The results indicate that the activation of K(+)(ATP) channels significantly contributes to the PTH-induced coronary vasodilation.