Related Experiment Video
Updated: Aug 4, 2026

Quantifying Agonist Activity at G Protein-coupled Receptors
Published on: December 26, 2011
Cyclic GMP mimics the muscarinic response in Xenopus oocytes: identity of ionic mechanisms
Abstract:
Acetylcholine (AcCho) elicits four distinct membrane responses in Xenopus oocytes; the responses can be studied by using the voltage clamp technique. The fastest of the responses, a transient inward current (D1 response), is muscarinic, being evoked by oxotremorine and blocked by atropine but not by curare or hexamethonium. The action of AcCho is cooperative, three transmitter-receptor complexes being required to cause a membrane conductance change, and the dose-response curve in most cases can be fitted by an equation assuming the existence of two binding sites with an affinity ratio of about 11. Guanosine 3',5'-cyclic monophosphate and the 8-bromo and dibutyryl derivatives cause a response similar to D1 in both its time course and the underlying ionic mechanism. The nucleotide-generated response has a smaller amplitude than the AcCho-generated D1.
More Related Videos
07:24Xenopus Oocytes: Optimized Methods for Microinjection, Removal of Follicular Cell Layers, and Fast Solution Changes in Electrophysiological Experiments
Published on: December 31, 2016
07:16Methods for the Discovery of Novel Compounds Modulating a Gamma-Aminobutyric Acid Receptor Type A Neurotransmission
Published on: August 16, 2018
Related Concept Videos
Activation and Inactivation of G Proteins
G-Protein Gated Ion Channels
Sensory organs,...
GPCRs Regulate Adenylyl Cylase Activity
Two...
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Cholinergic Receptors: Muscarinic
The subtypes M1, M3, and M5 couple with the Gq subunit and activate the phospholipase C (PLC) activity, mobilizing intracellular Ca2+. Activation...
Direct-Acting Cholinergic Agonists: Chemistry and Structure-Activity Relationship
The direct-acting...