Single channel recordings from synaptosomal AMPA receptors.

TY - JOUR

T1 - Single channel recordings from synaptosomal AMPA receptors.

AU - Vaithianathan, Thirumalini

AU - Manivannan, Kandiah

AU - Kleene, Ralf

AU - Bahr, Ben A

AU - Dey, Markus P

AU - Dityatev, Alexander

AU - Suppiramaniam, Vishnu

PY - 2005

Y1 - 2005

N2 - Synaptic glutamate receptors play a prominent role in the excitatory neurotransmission in the vertebrate central nervous system. Although elucidation of the functional properties of glutamate receptors using electrophysiologic analyses has yielded important information, methodological and technological limitations have prevented direct measurement of single channel properties of synaptic receptors. Here, we have isolated murine mossy fiber synaptosomes and reconstituted them into small artificial lipid bilayers to characterize the single-channel properties of synaptic alpha amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-subtype glutamate receptors. The reconstituted synaptosomal receptors were activated by nanomolar concentrations of AMPA and blocked by a potent AMPA receptor antagonist. The synaptosomal AMPA receptors exhibited channel conductances of 14-56 pS and linear current-voltage relationship. The open and closed dwell time distributions of single channel currents were best described by three exponentials. These channels frequently exhibited burst behavior with long burst duration of approx 60 ms. Experiments with multichannel recordings revealed that steady state probabilities could not be fitted using a binomial distribution, indicating a cooperative channel gating behavior that would account for larger membrane currents. Our findings suggest that isolation, reconstitution into lipid bilayers, and subsequent single channel analysis of synaptosomal receptors is a useful method for investigation of synaptic AMPA receptors.

AB - Synaptic glutamate receptors play a prominent role in the excitatory neurotransmission in the vertebrate central nervous system. Although elucidation of the functional properties of glutamate receptors using electrophysiologic analyses has yielded important information, methodological and technological limitations have prevented direct measurement of single channel properties of synaptic receptors. Here, we have isolated murine mossy fiber synaptosomes and reconstituted them into small artificial lipid bilayers to characterize the single-channel properties of synaptic alpha amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-subtype glutamate receptors. The reconstituted synaptosomal receptors were activated by nanomolar concentrations of AMPA and blocked by a potent AMPA receptor antagonist. The synaptosomal AMPA receptors exhibited channel conductances of 14-56 pS and linear current-voltage relationship. The open and closed dwell time distributions of single channel currents were best described by three exponentials. These channels frequently exhibited burst behavior with long burst duration of approx 60 ms. Experiments with multichannel recordings revealed that steady state probabilities could not be fitted using a binomial distribution, indicating a cooperative channel gating behavior that would account for larger membrane currents. Our findings suggest that isolation, reconstitution into lipid bilayers, and subsequent single channel analysis of synaptosomal receptors is a useful method for investigation of synaptic AMPA receptors.

KW - Animals

KW - Mice

KW - Neurons/cytology/metabolism

KW - Ion Channels/metabolism

KW - Lipid Bilayers/metabolism

KW - Receptors, AMPA/metabolism

KW - Synaptic Transmission/physiology

KW - Synaptosomes/metabolism

KW - Animals

KW - Mice

KW - Neurons/cytology/metabolism

KW - Ion Channels/metabolism

KW - Lipid Bilayers/metabolism

KW - Receptors, AMPA/metabolism

KW - Synaptic Transmission/physiology

KW - Synaptosomes/metabolism

M3 - SCORING: Journal article

VL - 42

SP - 75

EP - 85

JO - CELL BIOCHEM BIOPHYS

JF - CELL BIOCHEM BIOPHYS

SN - 1085-9195

IS - 1

M1 - 1

ER -