I infected mice using 3.5% isoflurane in oxygen for about 5min or until their respirations have slowed to 1 second in between breaths.
I then quickly infect the mice with 100uL of my virus in PBS via oropharyngeal aspiration and place the mice back in their cage to recover.
This technique works well with young B6 mice (6-12wks), but each time I do this technique with the aged mice at least one ends up expiring after infection.
I'd like to avoid any deaths so please let me know if you have suggestions for ways to improve my technique.
Hi there,
3.5% is , in my view too high for aged mice; I would try with 2.5% (max 3%) and following instillation keep them in a separate box with 100% oxygen, for a few minutes observation. until they can sit up again before returning them to the homecage
Kind regards
Flora
Thank you for the advice - I will definitely try this!
With 2.5%, how long on average do the aged mice spend in the anesthesia chamber before their breathing has slowed enough for successful oropharyngeal aspiration?
Thanks again.
Hi ! You already mentioned that you wait until respiratory rate decreases to 60 breath/min. This rate should stay constant for 30 Sek at least and not decrease any further- similar to maintenance of anäesthesia on a facemask. The best is to try it out and find the balance.
Incidentally, are these mice SPF , free from any pathogens that could worsen their breathing with age ? Kind regrds
Flora