RESUMEN
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.
Asunto(s)
Presión Sanguínea/efectos de los fármacos , Hipoxia/fisiopatología , Ventilación Pulmonar/efectos de los fármacos , Frecuencia Respiratoria/efectos de los fármacos , Transmisión Sináptica/efectos de los fármacos , Aminofilina/administración & dosificación , Aminofilina/farmacología , Animales , Antagonistas del GABA/administración & dosificación , Antagonistas del GABA/farmacología , Hemodinámica/efectos de los fármacos , Hidroxibutiratos/farmacología , Inyecciones Intravenosas , Masculino , Picrotoxina/administración & dosificación , Picrotoxina/farmacología , Antagonistas de Receptores Purinérgicos P1/administración & dosificación , Antagonistas de Receptores Purinérgicos P1/farmacología , RatasRESUMEN
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.
Asunto(s)
Aminofilina/farmacología , Receptores de GABA-B/efectos de los fármacos , Respiración/efectos de los fármacos , Animales , Agonistas de Receptores GABA-B/farmacología , Hidroxibutiratos/farmacología , Masculino , Compuestos Organometálicos/farmacología , RatasRESUMEN
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.
Asunto(s)
Hipoxia , Picrotoxina/farmacología , Respiración/efectos de los fármacos , Aminofilina/farmacología , Animales , Broncodilatadores/farmacología , Antagonistas del GABA/farmacología , Hemodinámica/efectos de los fármacos , Hipocapnia , Masculino , Ratas , Receptores de GABA-A/metabolismoRESUMEN
Acute experiments on narcotized rats showed that intravenous infusion of GABA derivative lithium hydroxybutyrate induced different changes in hemodynamic and respiratory parameters in animals with high and low resistance to hypoxia. Rats highly resistant to hypoxia better tolerated lithium hydroxybutyrate treatment compared to low resistant animals.
Asunto(s)
Adaptación Fisiológica , Hemodinámica/efectos de los fármacos , Hidroxibutiratos/farmacología , Hipoxia/fisiopatología , Compuestos Organometálicos/farmacología , Respiración/efectos de los fármacos , Animales , Tolerancia a Medicamentos , Hidroxibutiratos/administración & dosificación , Hidroxibutiratos/química , Infusiones Intravenosas , Masculino , Compuestos Organometálicos/administración & dosificación , Compuestos Organometálicos/química , Ratas , Ácido gamma-Aminobutírico/química , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Effects of acute hypoxia on hemodynamics and respiration were studied in acute experiments on narcotized rats. The animals were divided into groups characterized by high, low-, and medium- resistance to hypoxia by the time of respiration arrest during inhalation of gas mixture containing 3% O2. Hemodynamic parameters of highly resistant animals were higher than in low-resistant rats throughout the entire hypoxic period. The development of a rare (with prolonged inspiratory phase) respiratory rhythm in highly resistant rats is an adaptive reaction, which allows them longer tolerate hypoxia compared to low-resistant animals.
Asunto(s)
Adaptación Fisiológica , Hemodinámica , Hipoxia/sangre , Hipoxia/fisiopatología , Respiración , Animales , Masculino , Ratas , Ratas EndogámicasRESUMEN
Acute experiments on cats showed that mild hypoxia did not disturb the balance between right and left ventricular outputs. Breaching 3% O(2) shifted this balance by reducing right ventricular output in cats with low resistance to hypoxia. Spontaneous breathing hypercapnic gas mixtures shifted this balance towards the left ventricular output. During artificial ventilation under open chest conditions, hypercapnia induced opposite changes and shifted the balance towards the right ventricular output.