Naslov
Propofol attenuates the phrenic long term facilitation in rats subjected to acute intermittent hypoxia

Autori
Carev, Mladen ; Valic, Maja ; Pecotic, Renata ; Karanovic, Nenad ; Valic, Zoran ; Pavlinac, Ivana ; Đogaš, Zoran

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
3. Hrvatski kongres neuroznanosti, Knjiga sežetaka / Šimić, Goran - Zagreb, 2009, 76-77

Skup
3. Hrvatski kongres neuroznanosti

Mjesto i datum
Zadar, Hrvatska, 24.09.2009. - 26.09.2009

Vrsta sudjelovanja
Poster

Vrsta recenzije
Domaća recenzija

Ključne riječi
propofol; phrenic nerve; hypoxia; long term facilitation; rat

Sažetak
Introduction: Long term facilitation (LTF) is sustained augmentation of respiratory motor output elicited by acute intermittent hypoxia (AIH), and is considered as a form of the central nervous system plasticity. It has been demonstrated in urethane-anesthetized rats. Propofol is an intravenous anesthetic widely used in humans. So far, the influence of propofol anesthesia on LTF in the model of AIH has not been studied in rats. Our hypothesis is that, there will be a significant difference in LTF between urethane and propofol anesthesia. Materials and methods: The phrenic nerve activity (PNA) was recorded in 14 adult, male, Sprague-Dawley rats, bilaterally vagotomized, paralyzed and mechanically ventilated. The phrenic nerve recordings monitored central respiratory activity. Phrenic nerve was dissected using dorsal approach at the level of C5 nerve rootlet, mounted on bipolar silver wire electrodes. The rats were placed in a prone position in a stereotaxic instrument. The animals were divided in 2 groups ; group U (urethane-anesthetized, 1.2 g/kg i.p., n=7) and group P (propofol-anesthetized, iv bolus 11.9 mg/kg + infusion 1.3 mg/kg/min, n=7). Rats were exposed to five, 3-min hypoxic episodes (FiO2=0.09), separated by 3 minutes of hyperoxia (FiO2=0.5). Peak phrenic nerve amplitude (PNA), burst frequency (f), inspiratory time duration (Ti), expiratory time duration (Te) and total respiratory cycle duration (Ttot) were analyzed during the first hypoxia and 15, 30 and 60 minutes after the final hypoxic episode, and compared to the baseline values prior to the first hypoxic episode. Results: Isocapnia was successfully maintained throughout the protocol. There was a significant increase of peak phrenic nerve amplitude (66.7 ± 8.6%, p<0.05) in urethane anesthetized group 60 minute after the last hypoxic episode compared to the baseline values, i.e. the LTF was observed. There were no significant changes in PNA in the urethane anesthetized group at 15- and 30th minute after the last hypoxic episode. In the propofol anesthetized group no significant changes of PNA were recorded in any time point after the last hypoxic episode, i.e. no LTF was observed. AIH did not elicit significant changes in phrenic burst frequency, as well as in breathing rhythm parameters (Ti, Te, Ttot) in both groups at all 3 time points after the last hypoxic episode. Regarding the first episode of AIH, PNA was significantly increased in both groups compared to baseline values (172.3 ± 2.0 % in the urethane anesthetized group vs 106.8 ± 16.9 % in the propofol anesthetized group, p<0.001), while phrenic burst frequency was significantly increased only in the urethane anesthetized group (53.0 ± 3.6 vs pre-hypoxic 36.5 ± 3.7 bursts/min, p<0.01). Conclusion: LTF, elicited by AIH, was attenuated in propofol-anesthetized rats. On the contrary, LTF was observed in urethane-anesthetized rats 60 minutes after the last hypoxia and was expressed as amplitude, but not frequency-LTF.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

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