Purchase this article with an account.
A.O. Koskelainen, J. Pahlberg; The General Anaesthetic Propofol Increases the Amplification Factor of Phototransduction in Dark-Adapted Mouse Rods . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1519.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To study the effect of propofol (2,6-diisopropylphenol), one of the predominant general anaesthetics, on the photoresponses of mouse rods. Methods: Aspartate-isolated rod photoresponses to 519 nm flashes were recorded by the electroretinogram (ERG) technique across isolated mouse (Mus musculus) retinas. The retinas were perfused from the photoreceptor side with Ringer solution at 22 °C or 36 °C. Propofol was dissolved in ethanol and the dissolution of propofol-ethanol stock solution in Ringer gave final propofol concentrations from about 6 µM up to 1.7 mM. The ethanol concentration was always 1 %. The amplification factor of phototransduction was determined by fitting the Lamb and Pugh model1 to the rising phase of "fractional responses". By this we refer to responses to less than half-saturating flashes, scaled by the numbers of photoisomerizations and normalized by the saturated response amplitude. Results: In darkness propofol increased the saturated photoresponse amplitude in a concentration-dependent manner at both temperatures. The maximal effect was obtained with approximately 600 µM propofol, which could even double the amplitudes. More interestingly, propofol strongly accelerated the rising phase of fractional responses. The largest rise observed in the amplification factor was about threefold. Ethanol itself slightly increased the saturated photoresponse amplitude but did not affect the amplification factor. Conclusions: Propofol increased the amplification factor of phototransduction in dark-adapted rods at constant temperature. To our knowledge, such an increase has been reported only once prior to this study: Calvert et al.2 showed that 50 % reduction in rhodopsin content in mice obtained by hemizygous knockout of rhodopsin increased the amplification constant by 70 %. By analogy with their interpretation, our present results might be explained by effectivized lateral diffusion of phototransduction proteins. 1Lamb, T.D. and Pugh, E.J. (1992), J. Physiol. 449, 719-758. 2Calvert et al. (2001), Nature, 411, 90-94.
This PDF is available to Subscribers Only