1356119

Developmental changes in expression of GABAA receptor-channels in rat intrinsic cardiac ganglion neurones.

Article date: 2005/2/26

PubMed ID: 1356119

Journal name: The Journal of physiology (ISSN: 0022-3751)

ABSTRACT

The effects of gamma-aminobutyric acid (GABA) on the electrophysiological properties of intracardiac neurones were investigated in the intracardiac ganglion plexus in situ and in dissociated neurones from neonatal, juvenile and adult rat hearts. Focal application of GABA evoked a depolarizing, excitatory response in both intact and dissociated intracardiac ganglion neurones. Under voltage clamp, both GABA and muscimol elicited inward currents at -60 mV in a concentration-dependent manner. The fast, desensitizing currents were mimicked by the GABA(A) receptor agonists muscimol and taurine, and inhibited by the GABA(A) receptor antagonists, bicuculline and picrotoxin. The GABA(A0) antagonist (1,2,5,6-tetrahydropyridin-4-yl)methyl phosphonic acid (TPMPA), had no effect on GABA-induced currents, suggesting that GABA(A) receptor-channels mediate the response. The GABA-evoked current amplitude recorded from dissociated neurones was age dependent whereby the peak current density measured at -100 mV was approximately 20 times higher for intracardiac neurones obtained from neonatal rats (P2-5) compared with adult rats (P45-49). The decrease in GABA sensitivity occurred during the first two postnatal weeks and coincides with maturation of the sympathetic innervation of the rat heart. Immunohistochemical staining using antibodies against GABA demonstrate the presence of GABA in the intracardiac ganglion plexus of the neonatal rat heart. Taken together, these results suggest that GABA and taurine may act as modulators of neurotransmission and cardiac function in the developing mammalian intrinsic cardiac nervous system.

Author List: Fischer Harald, Harper Alexander A, Anderson Colin R, Adams David J

Publication Types: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Article Date: 2005/02/24

Substances mentioned in the article: GABA-A Receptor Agonists; GABA-A Receptor Antagonists; Receptors, GABA-A; gamma-Aminobutyric Acid; Bicuculline;

Mesh terms: Animals; Animals, Newborn; Bicuculline/pharmacology; Female; GABA-A Receptor Agonists; GABA-A Receptor Antagonists; Ganglia, Autonomic/drug effects; Gene Expression Regulation, Developmental/drug effects; In Vitro Techniques; Membrane Potentials/drug effects; Myocardium/metabolism; Neurons/drug effects; Rats; Rats, Wistar; Receptors, GABA-A/biosynthesis; gamma-Aminobutyric Acid/pharmacology;

Citations: - 1660002

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