PURPOSE. To study deactivation of the rod photoresponse in infants using a paired-flash procedure. Rhodopsin content increases and scales the parameters of the activation of rod phototrans duction as rods develop. How...PURPOSE. To study deactivation of the rod photoresponse in infants using a paired-flash procedure. Rhodopsin content increases and scales the parameters of the activation of rod phototrans duction as rods develop. However, little is known about the kinetics of deactivation in the rods of young infants. METHODS. ERG responses to pairs of flashes were used to study the recovery of the rod response in 4- and 10- week-old infants and mature control subjects. The amplitudes of rod isolated a-wave responses to a probe flash (+ 3.3 log scot tds) presented 2 to 120 seconds after an equal-intensity test flash were measured. The interstimulus interval (ISI) at which the amplitude was half that of the response to the probe flash alone (t50) was determined by linear interpolation. RESULTS. Recovery time (t50) was significantly longer in infants than in adults (F=18.9, df 2, 32; P<0.01). The shape of the recovery function did not vary with age. The t50 values were inversely proportional to the parameters of activation of rod phototransduction. CONCLUSIONS. These results are evidence that the kinetics of deactivation in infants are slower and may be set by the proportion of rhodopsin isomerized.展开更多
文摘PURPOSE. To study deactivation of the rod photoresponse in infants using a paired-flash procedure. Rhodopsin content increases and scales the parameters of the activation of rod phototrans duction as rods develop. However, little is known about the kinetics of deactivation in the rods of young infants. METHODS. ERG responses to pairs of flashes were used to study the recovery of the rod response in 4- and 10- week-old infants and mature control subjects. The amplitudes of rod isolated a-wave responses to a probe flash (+ 3.3 log scot tds) presented 2 to 120 seconds after an equal-intensity test flash were measured. The interstimulus interval (ISI) at which the amplitude was half that of the response to the probe flash alone (t50) was determined by linear interpolation. RESULTS. Recovery time (t50) was significantly longer in infants than in adults (F=18.9, df 2, 32; P<0.01). The shape of the recovery function did not vary with age. The t50 values were inversely proportional to the parameters of activation of rod phototransduction. CONCLUSIONS. These results are evidence that the kinetics of deactivation in infants are slower and may be set by the proportion of rhodopsin isomerized.
