RESUMO
Respiratory rhythm changes and hypoxic ventilatory responses were studied in anesthetized albino rats after administration GABA and adenosine receptor antagonists. Intracisternal microinjection of picrotoxin induced pathological periodic breathing. Picrotoxin intravenous administration caused the increase of individual resistance to acute hypoxia. Aminophylline administration exerted the opposite effect. After pretreatment of hydroxybutyrate we observed different types of respiratory reactions to adenosine antagonist injection, which probably depended on the value of arterial blood pressure and cerebral hemodynamics.
Assuntos
Pressão Sanguínea/efeitos dos fármacos , Hipóxia/fisiopatologia , Ventilação Pulmonar/efeitos dos fármacos , Taxa Respiratória/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Aminofilina/administração & dosagem , Aminofilina/farmacologia , Animais , Antagonistas GABAérgicos/administração & dosagem , Antagonistas GABAérgicos/farmacologia , Hemodinâmica/efeitos dos fármacos , Hidroxibutiratos/farmacologia , Injeções Intravenosas , Masculino , Picrotoxina/administração & dosagem , Picrotoxina/farmacologia , Antagonistas de Receptores Purinérgicos P1/administração & dosagem , Antagonistas de Receptores Purinérgicos P1/farmacologia , RatosRESUMO
We studied changes in breathing pattern in nembutal-anaesthetized mongrel rats after administration of euphylline against the background of preliminary treatment with lithium hydroxybutyrate. Two types of external respiration responses to euphylline were observed; they depended on the initial blood pressure in systemic circulation and on its drop after euphylline administration. Thus, the reaction of the respiratory system to adenosine receptors blockade against the background of hydroxybutyrate pretreatment was associated with not only the effect of euphylline, but also the state of brain hemodynamics. The effects of euphylline on chemosensitive contour of the respiratory system regulation were also investigated. It was found that euphylline did not abolish desensitization of respiratory system to hypercapnia, but smoothed the response to hypoxia under conditions of GABA(b)-receptor activation.
Assuntos
Aminofilina/farmacologia , Receptores de GABA-B/efeitos dos fármacos , Respiração/efeitos dos fármacos , Animais , Agonistas dos Receptores de GABA-B/farmacologia , Hidroxibutiratos/farmacologia , Masculino , Compostos Organometálicos/farmacologia , RatosRESUMO
Organism's resistance to acute severe hypoxia (3% O2) was studied after administration of GABA(A) receptor antagonist picrotoxin and adenosine receptor antagonist euphylline (aminophylline) and after neutralization of secondary hypocapnia by adding 7% CO2 to the hypoxic mixture. Administration of picrotoxin to anesthetized rats increased animal resistance to hypoxia. The resistance to hypoxia decreased after treatment with euphylline. Neutralization of secondary hypocapnia by adding 7% CO2 to the hypoxic mixture had no effect on animal lifespan.