Dopamine modulates a voltage-gated calcium channel in rat olfactory receptor neurons.
Dopamine D2 receptors exist in the soma of rat olfactory receptor neurons. Actions of dopamine on the voltage-gated Ca(2+) channels in the neurons were investigated using the perforated whole-cell voltage-clamp. In 10 mM Ba(2+) solution, rat olfactory receptor neurons displayed the inward currents elicited by the voltage ramp (167 mV/s) and depolarizing step pulses from a holding potential of -91 mV. The inward Ba(2+) currents were greatly reduced by 10 microM nifedipine (L-type Ca(2+) channel blocker). The Ba(2+) currents were inhibited by the external application of dopamine. The IC(50) for the inhibition was about 1 microM. Quinpirole (10 microM, a D2 dopamine agonist) also inhibited the Ba(2+) currents. Quinpirole did not affect the activation and inactivation kinetics of the Ba(2+) currents. The results suggest that dopamine modulates the L-type Ca(2+) channels in rat olfactory receptor neurons via the mechanism independent of voltage.
Okada
Yukio
Y
Integrative Sensory Physiology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan. okada@net.nagasaki-u.ac.jp
Miyamoto
Takenori
T
Toda
Kazuo
K
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001464:Barium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D002478:Cells, Cultured; D004298:Dopamine / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D018034:Olfactory Receptor Neurons / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D019257:Quinpirole / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D018491:Dopamine Agonists; D019257:Quinpirole; D001464:Barium; D009543:Nifedipine; D004298:Dopamine