Heparin uncouples the muscarinic receptors from GKprotein in the atrial cell membrane of the guinea-pig heart

✍ Scribed by Hiroyuki Ito; Reiko Takikawa; Mari Iguchi; Eiji Hamada; Tsuneaki Sugimoto; Yoshihisa Kurachi

• Publisher: Springer
• Year: 1990
• Tongue: English
• Weight: 264 KB
• Volume: 417
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00370783

✦ Synopsis

The effects of heparin on activation of the G protein-gated muscarinic K + channel were examined in atrial cells of guinea-pig heart.

The inside-out patch clamp technique was used.

The pipette solution contained i.i ~M acetylcholine (ACh).

In the insideout patches, intracellular GTP activated the muscarinic K + channel.

When heparin (0.05-5 units/ml) was further added to the intracellular side of the patch membrane, the channel openings were depressed in a concentration-dependent fashion.

The effects of heparin were reversible after wash-out.

Heparin did not affect GTP-yS-induced activation of the K + channel. Therefore, it is suggested that heparin may uncouple the muscarinic receptors from G K protein in the cardiac atrial cell membrane.