Parathyroid hormone: an endogenous modulator of cardiac calcium channels.
We have tested the effects of the active 1-34 amino acid sequence of rat parathyroid hormone (PTH) on Ca2+ channel activity in neonatal rat ventricular cells. Rat PTH (30 pM to 10 nM) increased depolarization-induced Ca2+ influx into these cells, an effect that was abolished by 1 microM nifedipine. The 1-34 amino acid sequence of bovine PTH also stimulated Ca2+ influx in control cells but not in cells pretreated with cholera toxin. Rat PTH also elevated adenosine 3',5'-cyclic monophosphate accumulation in these ventricular myocytes. Whole cell voltage-clamp recordings confirmed a stimulatory effect of rat PTH on cardiac L-type Ca2+ channels. Cell-attached single channel recordings revealed an increase in the probability of channel opening as the primary mechanism for the enhancement of Ca2+ current. Taken together these results suggest an important role for PTH as an endogenous modulator of cardiac L-type Ca2+ channels.
Rampe
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Marion Merrell Dow Research Institute, Cincinnati, Ohio 45215.
Lacerda
A E
AE
Dage
R C
RC
Brown
A M
AM
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004553:Electric Conductivity; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006352:Heart Ventricles / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D010281:Parathyroid Hormone / Q000494:pharmacology* / Q000502:physiology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D016276:Ventricular Function
D015220:Calcium Channels; D010281:Parathyroid Hormone; D000242:Cyclic AMP; D007545:Isoproterenol; D011188:Potassium; D002118:Calcium