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BSSC94
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Literature
38 records
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from acutely isolated rat neocortical pyramidal neurones using the whole-cell
patch technique to examine the effect of agents that block P-type calcium
channels and to compare their effects to those of omega-conotoxin GVIA
(omega-CgTX) and nifedipine. 2. When applied at a saturating concentration
(100 nM) the peptide toxins omega-Aga-IVA and synthetic omega-Aga-IVA blocked
31.5 and 33.0% of the HVA current respectively. 3. A saturating concentration
of nifedipine (10 microM) inhibited 48.2% of the omega-Aga-IVA-sensitive
current, whereas saturating concentrations of both omega-Aga-IVA (100 nM) and
omega-CgTX (10 microM) blocked separate specific components of the HVA
current. 4. Partially purified funnel web spider toxin (FTX) at a dilution of
1:1000 blocked 81.4% of the HVA current and occluded the inhibitory effect of
omega-Aga-IVA. Synthetic FTX 3.3 arginine polyamine (sFTX) at a concentration
of 1 mM blocked 61.2% of the HVA current rapidly and reversibly. The effects
of sFTX were partially occluded by pre-application of omega-Aga-IVA. We
conclude that neither FTX nor sFTX blocked a specific component of the HVA
current in these cells. 5. In view of the specificity of omega-Aga-IVA for
P-type calcium channels in other preparations and for a specific component of
the HVA current in dissociated neocortical neurones we conclude that about 30%
of the HVA current in these neurones flow through P-channels.
