РЕАКЦИИ ДЫХАНИЯ НА АКТИВАЦИЮ ГАМКА- И ГАМКВ-РЕЦЕПТОРОВ ПАРАФАЦИАЛЬНОЙ РЕСПИРАТОРНОЙ ГРУППЫ СПЕЦИФИЧЕСКИМИ АГОНИСТАМИ

Abstract

The purpose of the paper is to conduct comparative analysis of GABAА and GABAВ receptors of the parafacial respiratory group (pfRG) in central mechanisms of respiratory regulation in adult rats. Materials and Methods. The authors studied the reactions of external respiration and diaphragmatic muscle on microinjections of muscimol and baclofen solutions (10-6 M, 200 nl) in the region of pFHR on rats, anesthetized with urethane. Injections were administered through a glass microcannula according to stereotactic coordinates. A spirogram and electromyogram (EMG) of the diaphragm were recorded in the initial state and within 60 minutes after microinjection of the abovementioned agonists of GABAА and GABAВ receptors. Results. Microinjections of muscimol, the agonist of GABAA receptors, in pfGR had an inhibitory effect on respiration. The inhibitory effect was characterized by a short latent period. Minute lung ventilation decreased in rats due to changes in tidal volume and respiratory rate, while the inspiratory and expiratory time increased. On the EMG of the diaphragm, the oscillation amplitude decreased, while the duration of inspiratory bursts and inter-burst intervals increased. Microinjections of baclofen solution, GABAВ agonist receptor, in pfGR also caused respiratory depression, but with a longer latency period. In that case, a decrease in pulmonary ventilation was provided by a decrease in tidal volume in combination with inspiration lengthening. Changes in the breathing pattern corresponded to a decrease in the oscillation amplitude and an increase in the duration of inspiratory bursts on the EMG of the diaphragm. Conclusions. The role of pfGR in the respiratory regulation is mediated by ionotropic GABAА- and metabotropic GABAB-receptors. GABAA-receptors in the pfHR area contribute to expiration-inspiration regulation, while GABAB-receptors are predominantly involved in inspiratory activity modulation. Keywords: parafacial respiratory group, GABAA-receptors, GABAB-receptors, muscimol, baclofen, external respiration, electromyogram of the diaphragm.