Effects of nitrendipine on the voltage-sensitive calcium channel in mammalian sensory neurons.
We examined the ability of nitrendipine, a calcium antagonist believed to block the voltage-sensitive calcium channels in a number of excitable membranes, to affect the calcium spike duration and rate of rise (Dv/Dt) in 4-week-old cultured mouse dorsal root ganglion neurons. Concentrations of 10 nM-1.0 microM nitrendipine reduced but did not eliminate calcium spike as measured by the rate of rise. These results were obtained at either 22 degrees or 37 degrees C in solutions containing 5 mM calcium. A similar lack of total block was seen with prolonged incubation in sodium-free recording media containing 1 microM tetrodotoxin (TTX), 1.8 mM calcium, and 1 microM nitrendipine. Calcium spike duration was affected in an inconsistent manner by nitrendipine and other 1,4 dihydropyridines. Cobalt (10 mM) totally blocked the voltage-dependent calcium mechanism as measured by either the spike duration or the rate of rise. We conclude that calcium influx through the voltage-sensitive calcium channel in mouse dorsal root ganglion neurons is not blocked by even high concentrations of nitrendipine.
M J
MJ
Litzinger
P G
PG
Nelson
R Y
RY
Pun
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D002478:Cells, Cultured; D004095:Dihydropyridines; D004558:Electric Stimulation; D000431:Ethanol / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000166:cytology; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D009414:Nerve Growth Factors / Q000494:pharmacology; D009475:Neurons, Afferent / Q000502:physiology*; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009568:Nitrendipine; D014677:Pharmaceutical Vehicles; D011725:Pyridines / Q000494:pharmacology; D011930:Reaction Time; D013696:Temperature
D004095:Dihydropyridines; D007473:Ion Channels; D009414:Nerve Growth Factors; D014677:Pharmaceutical Vehicles; D011725:Pyridines; D000431:Ethanol; C038806:1,4-dihydropyridine; D009568:Nitrendipine; D009543:Nifedipine