“The obstructive apnoeas liable … occur after an L‐tryptophan load (50 mg kg‐1) were prevented … blocking the 5‐HT receptor with methysergide (50 mg kg‐1, n = 5) or by blocking the 5‐HT biosynthesis … applying p‐chlorophenylalanine (PCPA) pretreatment at birth (300 mg kg‐1, n = 7).”