engleski

Respiratory acitivity is altered by injections of bicuculline into the rat ventral respiratory group

Breathing is a complex behavior which must be precisely regulated by the brain via respiratory neurons located throughout ventrolateral medulla to control arterial blood gases and acid-base status within the narrow limits compatible with life. The main objective of this study was to demonstrate the important role of GABAA receptors in the respiratory pattern/rhythm generation of the different regions of ventral respiratory group (VRG), as shown in the phrenic nerve acitivity. In urethane-anaesthetized, and bilaterally vagotomized adult male Wistar rats, arterial blood pressure, and respiratory motor output of the phrenic nerve was recorded. The rats were placed in a prone position in a stereotaxic instrument. Glass micropipettes were used for drug delivery. The single or multiple barrel micropipettes were filled with bicuculline (250 mM), DLH (Dl-homocysteic acid, 10 mM), or artificial cerebrospinal fluid (aCSF), and used for unilateral drug delivery. At the end of each experiment, the injection pipette was used to mark injection site with diluted India ink for subsequent histological reconstruction of the injection site. Unilateral microinjections of DLH into the different regions of VRG resulted in phasic or tonic nonphasic increase of phrenic nerve discharge, or apnea. The evoked responses by the unilateral microinjections of bicuculline differed due to the location of injection site in a rostrocaudally dependent manner. Several types of respiratory responses were recorded, such as reversible increases of respiratory rate, and the phrenic nerve discharge amplitude, transitional apnea, or dysrhythmic breathing pattern. These data suggest the important role for GABAA receptors in the generation of respiratory pattern/rhythm and their location in the functionally distinct compartments of the VRG.

GABA; γ -amino-butyric acid; GABAA-receptor; bicuculline; VRG; ventral respiratory group

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