Adrenaline induced changes in the metabolism of glycogen in the teleost retina

A study on the influences of adrenaline upon the metabolism of glycogen in fish retina is presented. The glycogen in the retina of the fish Eugerres plumieri amounted to approximately 7·5 mg glucose/10 g tissue wet weight of which 5·8+0±81 S.D. was present in the lyo-form and 1·7+0·41 S.D. in the desmo-form. The phosphorylase A activity in this tissue was found to be 36·5 μg P/g tissue wet weight/min, which represents 68 % of the total phosphorlyase activity. A definite effect of administered adrenaline upon the retinal glycogen could be observed only when conditions facilitating the penetration of this substance into the retina were given. A dose of 100 μg/kg body weight of adrenaline injected to the animals previously pretreated with 10 mg/kg of isocarboxazid and 20 ml of 20% v/v aqueous solution of ethanol showed a significant increase in phosphorylase activity and a close to 50% drop in the retinal lyo-glycogen. The highest penetration of adrenaline into the retina was observed 20 to 40 min after the injection of adrenaline into a fish pretreated with isocarboxazid 4 h and ethanol 20 min prior to the administration of the amine. Under these conditions the glycemia went up from 70mg% to 90mg% and the MAO-activity dropped from a value of 85 ug 4 HOQ/g tissue wet weight/30 min to zero.