Akademik Veri Yönetim Sistemi
Turk Anesteziyoloji ve Reanimasyon, cilt.24, sa.6, ss.244-249, 1996 (Scopus)
The present study was undertaken to investigate the ventilatory response to sustained (20 min.) isocapnic moderate hypoxia and the possible role of adenosine in hypoxic depression in anesthetized cats. The experiments conducted in 13 cats anesthetized with thiopentone (Na (30 mg/kg IP). Respiratory frequency (f/min.) tidal volume (V(T)), ventilation minute volume (V(E)) and systemic arterial blood pressure were recorded during air and 20 min. hypoxic gas mixture (14% O2-86% N2) breathing. PaO2 and PaCO2 were determined. Isocapnia was maintained by adding fractions of 1% CO2 in to the inspired hypoxic gas mixture PaCO2 was maintained at its prehypoxic air breathing phase volume. On hypoxic gas mixture breathing V(T) and V(E) values of the control animals increased significantly, at 5 min. to (49.98% ± 5.9), (53.42% ± 6.48) above the prehypoxic air phase value taken as 100. After that, the magnitude in increase in V(T) and V(E) declined gradually. At 20 min. of hypoxia V(T) and V(E) were less than that in prehypoxic air phase (17.49% ± 6.98), (16.32% ± 7.03). In cats injected with an adenosine antagonist (theophylline 13.6 mg/kg IV), f, V(T) and V(E) increased significantly at 5 min. of hypoxia. No decrease in the magnitude of ventilatory response was observed during the 20 min. hypoxic phase. At 20 min. of hypoxia f, V(T) and V(E) were (8.27% ± 2.46), 29.97% ± 7.57), (39.23% ± 8.22) higher than that in prehypoxic stage. In cats injected with theophylline (0.51 mg/kg) by cisternal punction V(T) and V(E) increased significantly at 5 min. of hypoxia. At 20 min. of hypoxia V(T) and V(E) were (26.58% ± 7.0) and (30.86% ± 8.46) higher than that in prehypoxic air phase. The results of this study show that accumulation of adenosine in the brain during hypoxia seems to reduce the response of the central mechanisms to chemoreceptor impulses.