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Adenosine-induced slow ionic currents in the Xenopus oocyte.
Nature
|August 5, 1982
Summary
Adenosine and its related compounds trigger distinct cell responses. In Xenopus oocytes, these purinergic receptors mediate a chloride-dependent depolarization followed by a potassium-dependent hyperpolarization.
Area of Science:
- Cellular electrophysiology
- Purinergic signaling
Background:
- Adenosine and its phosphorylated congeners (e.g., ATP, ADP, AMP) elicit membrane responses in excitable tissues, potentially causing cell inhibition via hyperpolarization.
- The precise ionic mechanisms underlying these purinergic responses remain incompletely understood, particularly lacking investigation via standard electrophysiological techniques like voltage-clamping.
Purpose of the Study:
- To investigate the ionic mechanisms of purinergic receptor-mediated responses in Xenopus oocytes.
- To characterize the electrophysiological and biochemical properties of purinergic receptors in a well-defined giant cell model.
Main Methods:
- Utilized standard intracellular voltage-clamping techniques to study membrane responses in Xenopus oocytes.
- Investigated adenosine-induced currents and their ionic basis.
Main Results:
- Adenosine triggered slow membrane responses, comprising an initial transient depolarizing (D) current carried by chloride (Cl-) ions.
- This was followed by a sustained hyperpolarizing (H) current mediated by potassium (K+) ions.
- The potency order for the D current was ATP ≈ ADP > AMP ≈ Adenosine, while the order was reversed for the H current.
Conclusions:
- Purinergic receptors in Xenopus oocytes mediate distinct ionic currents, involving chloride influx and potassium efflux.
- These findings elucidate the ionic mechanisms of purinergic signaling in a non-excitable cell model, providing a basis for further research in excitable tissues.