- 貨號 Cat. No.
- P-270
- 規格 Size
- 1 mg 5mg 5x1mg 5mg 10mg
Description
Pimaric Acid (PiMA)
A Novel Opener of KCa1.1 Channels
Sizes: |
1 mg |
5 x 1 mg |
5 mg |
10 mg |
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Bioassay: |
PiMA applied to HEK cells expressing KCa1.1 channels, reduced a voltage dependent dye fluorescent signal, which was correlated to K+ channel increased activity. Its effects were assayed in such cells, using the whole cell and excised patch configurations of the patch clamp technique.1 We tested PiMA activity by recording from Xenopus oocytes injected with the KCa1.1 mRNA, using two-electrode voltage clamp (see figure). In the oocyte the effect of PiMA was ten fold weaker compared to HEK cells. |
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Enhancement of BK channel amplitude by 50 mM PiMA.
Left: time course of KCa1.1 channels amplitude, with application of 50 mM PiMA and 200 nM Charybdotoxin (Chtx). Currents were recorded from Xenopus oocytes injected with the KCa1.1 mRNA and were elicited by a 100 ms pulse to 0 mV from holding potential of ?00 mV. Pulses were delivered every 10 seconds. The bars at the top indicate the period of the indicated drug application. Currents were normalized to the values of controls. The red green and blue symbols and the letters mark the traces that are shown on the right.
Right: example traces of control (a, red), PiMA activated (b, green) and chtx inhibited (c, blue) KCa1.1currents taken from the experiment shown on the left.
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PiMA activation of KCa1.1 channels is voltage dependent. The amount of activation by PiMA was assayed by normalizing each response to its control current amplitude. All responses were simultaneously gathered by using a stepwise voltage protocol. |
1.
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Imaizumi, Y. et al. (2002) Mol. Pharmacol. 62, 836. |
PiMA was found to be a potent opener of KCa1.1 (large conductance Ca2+ activated K+ (BK)) channels. 1mM PiMA doubled the current carried via BK channels and this effect increased dose dependently. PiMA increases the open probability of single BK channels by shifting both its voltage and Ca2+ dependence to more hyperpolarized voltages.1 BK channels that were activated by PiMA retain their charybdotoxin sensitivity (see figure and 1).
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