Calcium-dependent chronotropic action of bovine parathyroid hormone (1-34) in isolated atria of Japanese quail, Coturnix coturnix japonica

Abstract

The involvement of extracellular calcium in the chronotropic action of parathyroid hormone (PTH) in isolated quail atria was studied. Bovine (b) PTH-(1-34) caused dose-dependent increases in the atrial beating rate. The PTH-induced positive chronotropism was significantly attenuated by lowering the extracellular calcium concentration or by using the calcium channel antagonists verapamil and D600. This suggests the importance of calcium influx in the cardiac action of PTH. beta-Adrenergic blockade with propranolol did not affect the responses to bPTH-(1-34). This further substantiates the previous findings that the PTH action is independent of cardiac beta-adrenoceptor stimulation.