ATP-evoked membrane responses in Xenopus oocytes

Area of Science:

• Cellular and Molecular Physiology
• Neuroscience
• Pharmacology

Background:

• Adenosine triphosphate (ATP) acts as a signaling molecule in various biological systems.
• Purinergic signaling, involving ATP and related compounds, plays a crucial role in cellular communication.
• Xenopus laevis oocytes are a well-established model system for studying ion channels and receptor function.

Purpose of the Study:

• To investigate the characteristics of ATP-evoked currents in Xenopus laevis oocytes.
• To identify the ionic basis and pharmacological properties of these responses.
• To explore the potential involvement of different purinoceptor types.

Main Methods:

• Voltage-clamp electrophysiology was employed to measure membrane currents.
• Intracellular drug injections were used to assess the effects of specific compounds.
• Xenopus laevis oocytes were utilized as the experimental model.

Main Results:

• ATP evoked a biphasic depolarizing current, comprising fast (D1) and slow (D2) components, primarily carried by chloride ions.
• The response was more pronounced with ATP and ADP compared to AMP or adenosine.
• The D2 component was occasionally obscured by an ATP-evoked potassium hyperpolarizing current, sensitive to theophylline and mediated by P1 purinoceptors.
• Neither theophylline nor quinidine sulphate blocked the primary depolarizing current.

Conclusions:

• Xenopus laevis oocyte membranes possess at least two distinct purinoceptor types.
• These purinoceptors are coupled to different sets of ion channels, mediating distinct cellular responses.
• The findings contribute to understanding purinergic signaling mechanisms in oocytes.