Intratracheal Instillation of PAAs in Rats

Doses of 0.2 mg (0.8 mg/kg BW) and 1.0 mg (4.0 mg/kg BW) of Non-CL-PAA and CL-PAA suspended in 0.4 mL distilled water were administered to the lungs of rats (12 weeks old) in single intratracheal instillations. Rats were intratracheally instilled under anesthesia by sevoflurane (Pfizer Japan, Tokyo, Japan) inhalation. Briefly, a laryngeal extension was performed using a laryngoscope blade (MAC1, Rudolf Riester GmbH, Jungingen, Germany), an animal feeding needle (KN-348, Natsume Seisakusho Co., Ltd., Tokyo, Japan) was inserted directly into the trachea, and the suspension was manually injected. Then, 3 mL of air twice with a syringe from the animal feeding needle was inserted into the trachea. The rats were then allowed to awaken spontaneously and were observed periodically. Single intratracheal instillations of 0.2 mg and 1.0 mg of Non-CL-PAA and CL-PAA were performed at different times, and the single intratracheal instillations were conducted a total of two times. The control group received distilled water, and a control group was established for each intratracheal instillation. Dosages of 0.2 and 1.0 mg/rat were used in the intratracheal instillation of the PAAs. This maximum dose was set assuming human exposure and to avoid overload in the lung [10 (link)].