Effect of ambient temperature on respiratory chemoreflex in unanaesthetized kittens

We compared the respiratory responses to breath-by-breath alternations of air and 14% oxygen (hypoxia run), air and 5% CO2 (CO2 run) or air from two gas lines (control run) at ambient temperatures of 25-26 degrees C and 30-31 degrees C in nine kittens at 3-7, 11-18 and 30-39 days post-natal age. Chemoreflex responses were measured from alternations in inspiratory and expiratory variables during test runs and compared with those of control runs. At 25-26 degrees C, no significant respiratory alternations were present in hypoxia runs at days 3-7, while alternations were significant at older ages. In CO2 runs alternation was significant at each age group. At 30-31 degrees C, no significant respiratory alternation was present in either hypoxia or CO2 runs for any age group. Thus respiratory chemoreflexes decrease at a warmer environmental temperature in kittens. This may explain how elevated environmental temperature predisposes neonates to respiratory failure.