Melatonin inhibits high voltage activated calcium currents in cultured rat dorsal root ganglion neurones.
The actions of melatonin on high-voltage activated calcium channels (HVACC) and intracellular free Ca(2+) concentration in cultured dorsal root ganglion (DRG) neurones from neonatal rats were investigated using the whole-cell patch clamp and the fura-2 fluorescence ratio Ca(2+)-imaging techniques. HVACC were pharmacologically and biophysically isolated and the effects of melatonin were investigated. Extracellular application of melatonin inhibited HVACC in a dose dependent manner. In calcium imaging experiments, application of extracellular recording medium containing 30 mM KCl evoked increases in intracellular free Ca(2+) that were dependent upon external Ca(2+) ions. This increase was prevented by both low (10 microM) and high dose (100 microM) of melatonin pre-treatment. The results of this study indicate that the pineal hormone melatonin has inhibitory actions on voltage dependent calcium entry in cultured rat DRG neurones.
Ayar
A
A
Firat University, Faculty of Medicine, Department of Pharmacology, TR-23200 Elazig, Turkey. a.ayar@mailexcite.com
Martin
D J
DJ
Ozcan
M
M
Kelestimur
H
H
D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D015220:Calcium Channels / Q000502:physiology*; D002478:Cells, Cultured; D005456:Fluorescent Dyes; D016257:Fura-2; D005727:Ganglia, Spinal / Q000166:cytology*; D008550:Melatonin / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D000927:Anticonvulsants; D015220:Calcium Channels; D005456:Fluorescent Dyes; D008550:Melatonin; D011188:Potassium; D016257:Fura-2