Effects of xylazine and ketamine on the acoustic reflex and brain stem auditory-evoked response in the cat.
The acoustic reflex (AR) and brain stem auditory-evoked response (BAER) were recorded in adult cats 5 minutes after IM administration of xylazine (1 mg/kg) and after IM administration of ketamine (10 mg/kg). Ipsilateral and contralateral AR were recorded at 10 and 20 dB above acoustic reflex threshold 5 minutes after xylazine administration and 5 and 35 minutes after ketamine administration. Monaural BAER were recorded 5 minutes after xylazine and 5 and 35 minutes after ketamine, using stimulus intensities of 90-, 80-, and 70-dB hearing level (HL). Additional BAER were recorded at 10, 15, and 25 minutes after ketamine, using the 90-dB HL stimulus. Pre- and postinjection comparisons were made for threshold, latency, and amplitude of the AR and for latency and amplitude of waves I through VI of the BAER. At both stimulus intensities before and after ketamine administration threshold for the ipsilateral reflex was significantly lower (P greater than 0.05) than for the contralateral reflex. The threshold, latency, and amplitude of the AR were unaffected (P greater than 0.05) by the injection of ketamine after xylazine. The amplitude of BAER waves was not affected (P greater than 0.05) by ketamine after xylazine for each of the 3 stimulus intensities. Latency of the 90-dB HL-evoked response was increased (P less than or equal to 0.05) for waves III/IV at 5 and 35 minutes after ketamine, and for wave V at each of the postinjection times, except at postinjection minute 15.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D001933:Brain Stem / Q000187:drug effects* / Q000502:physiology; D002415:Cats; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005260:Female; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D012022:Reflex, Acoustic / Q000187:drug effects*; D013843:Thiazines / Q000494:pharmacology*; D014991:Xylazine / Q000494:pharmacology*
D013843:Thiazines; D014991:Xylazine; D007649:Ketamine