Retinal Slice Preparation from Sprague Dawley Rats

Sprague Dawley rats were born and raised in the animal facility of the University of Valparaiso, held at 20–30 °C under a 12 h photoperiod with water and food ad libitum. Retinal slices were prepared from 3–4 week-old rats irrespective of sex or weight, by procedures described previously13 (link). The experimental protocols were approved by the bioethics committee of the University of Valparaiso and in accordance with the bioethics and biosafety regulation of the Chilean Research Council (CONICYT). Briefly, rats were anesthetized deeply by halothane inhalation and sacrificed by decapitation. Eyes were quickly removed and the retina was carefully separated from the sclera in a chamber with extracellular solution, containing (in mM): 119 NaCl, 23 NaHCO₃, 1.25 NaH₂PO₄, 2.5 KCl, 2.5 CaCl₂, 1.5 MgSO₄, 20 glucose and 2 Na⁺ pyruvate, aerated with 95% O₂ and 5% CO₂, reaching a pH of 7.4. A piece of central retina was embedded in type VII agarose (Sigma), and cut with a vibratome (Leica VT1000S) to 200 μm thickness. Retinal slices were transferred to the recording chamber, sustained by a U-shaped platinum wire, and superfused with oxygenated extracellular solution (flow rate 1 ml/min) at room temperature (20 °C) under conditions of low photopic background illumination (100 lux).