Expression and characterization of g protein‐activated inward rectifier k⁺ channels in xenopus oocytes

Abstract

The G protein‐activated inwardly rectifying K⁺ channel (GIRK1) was coex‐pressed in Xenopus oocytes along with the 5‐HTia receptor, a 7‐helix receptor known to be coupled to K⁺ channels in many neural tissues. Thus, the activation of the 5‐HT_1A receptor by its agonist leads to the opening of GIRK1. The GIRK1 current was measured using the two electrode voltage clamp technique with bath application of 5‐HT in the presence of various external potassium concentrations [K⁺]_o. GIRK1 showed a strong inward rectification since only hyperpolarizing voltages evoked inward currents. K⁺ was the major ion carrier as evidenced by about 44 mV voltage shift corresponding to a 10‐fold external [K⁺] change. 5‐HT induced a concentration‐dependent inward K⁺ current (EC ₅₀=10.7nM) which was blocked by Ba²⁺ Pertussis toxin (PTX) pre‐treatment reduced the K⁺ current by as much as about 70%, suggesting that PTX‐sensitive G protein (Gi or G_o type) are involved in the 5‐HT_1A receptor‐GIRK1 coupling in Xenopus oocytes

Key words:

• Xenopus oocytes
• G protein‐activated inward rectifier
• Voltage clamp Pertussis toxin sensitivity

Notes

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