The effects of parathyroid hormone on L‐type voltage‐dependent calcium channel currents in vascular smooth muscle cells and ventricular myocytes are mediated by a cyclic AMP dependent mechanism

Abstract

The present study demonstrated that L channel currents were decreased in smooth muscle cells, and increased in ventricular myocytes by both bovine parathyroid hormone, (bPTH‐(1–34)), and dibutyryl cyclic AMP (db‐cAMP), using the whole cell version of the patch clamp technique with Ba²⁺ as the charge carrier. The effects of bPTH‐(1–34) and db‐cAMP on L channel currents were additive but not synergistic. Furthermore, the effects of bPTH‐(1–34) on L channel currents in these 2 cell preparations were abolished in the presence of a cAMP antagonist. These results suggest that the effects of bPTH‐(1–34) on L channel currents in vascular smooth muscle cells and ventricular myocytes are mediated by a cAMP‐dependent mechanism.