Isopimaric Acid

Isopimaric Acid

A Novel Opener of K_Ca1.1 Channels

Product#:

I-370

Sizes:

1 mg

5 x 1 mg

5 mg

10 mg

Isopimaric acid (originalLy isolated from terpenoids) was found to be a potent opener of K_Ca1.1 (large conductance Ca²⁺ activated K⁺-BK) channels. 1mM Isopimaric acid doubled the current carried via K_Ca1.1 channels and this effect increased dose dependently. In analogy to the effects of pimaric acid, isopimaric acid may increase the open probability of single K_Ca1.1 channels by shifting both its voltage and Ca²⁺ dependence to more hyperpolarized voltages.¹ K_Ca1.1 channels that were activated by Isopimaric acid retain their Charybdotoxin sensitivity.

M.W.:

302 Da

Purity:

>99%

Bioassay:

Isopimaric acid applied to HEK cells expressing KCa1.1 (BK) 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 configuration of the patch clamp technique.1 We tested Isopimaric acid activity by recording from Xenopus oocytes injected with the KCa1.1 channel mRNA, using two-electrode voltage clamp (see figure). In the oocyte the effect of Isopimaric acid was ten fold weaker compared to HEK cells.

Legend: A. Enhancement of KCa1.1 channel amplitude by 10 mM Isopimaric acid. Left: time course of KCa1.1 channels amplitude, with application of 10 mM isopimaric acid. Currents were recorded from Xenopus oocytes injected with the KCa1.1 mRNA and were elicited by a 150 ms pulse that increases stepwise every 30 ms from +10 mV to +50 mV from holding potential of ?00 mV (see top trace on the right). Pulses were delivered every 10 seconds. Currents were normalized to the values of controls. All responses were simultaneously gathered by using a stepwise voltage protocol (right bottom).

References:

1.	Imaizumi, Y. et al. (2002) Mol. Pharmacol. 62, 836.