Differential effects of pCO2 and pH on the ERG and light peak of the perfused cat eye.

Hypercapnia has been shown to depress the ERG b-wave and also the light peak in vivo. To test if acidosis induced by elevation pCO2 affects the retina differently from that induced by HCl we used bicarbonate buffered and HEPES buffered perfusates, respectively, in isolated perfused feline eyes. Any decrease in pH from 7.4 to 7.1-7.0 depressed the b-wave and enhanced the flow rate of a perfusate. The light peak, in contrast, was depressed only be largely elevated pCO2. Preretinal measurements of pH in the perfused eye confirmed retinal acidosis. All effects were reversible.