Effects of telazol and nembutal on retinal responses

Purpose: Compare the effects of Nembutal, a barbiturate, and Telazol, a dissociative anesthetic, on photoreceptor and post-receptoral retinal responses. Methods: Dark adapted infant and adult albino rats were anesthetized with intraperitoneal injection of Nembutal or Telazol. ERG responses to full-field stimuli were recorded over a 6–8 log unit range from dim intensities at which the scotopic threshold response (STR) was observed to those that saturate the a-wave. The rod photoresponse, b-wave, oscillatory potentials (OPs), and STR parameters of rats in the Nembutal and Telazol groups were compared. Results: For both infants and adults, the saturated amplitudes of the photoresponse and the b-wave were larger in Telazol than Nembutal rats, but sensitivity of the photoresponse did not differ significantly between Telazol and Nembutal rats. The STR was seen only in the Telazol responses of adults. There was little differential effect of the two agents on the OPs. Conclusions: Photoreceptor and postreceptoral responses recorded under Nembutal and Telazol anesthesia differ significantly. These results may inform selection of anesthetic for studies of animal models.