Influences of isoproterenol pretreatment on cerebral cortical bindings of [3H]clonidine and [3H]dihydroalprenolol in infant and adult rats.
Specific bindings of [3H]clonidine and [3H]dihydroalprenolol [( 3H]DHA) to crude synaptic membranes were measured after cerebral cortical slices or synaptic membranes were pre-incubated with isoproterenol, 200 microM at 37 degrees C for 40 min, in 7- and 70-day-old rats. Isoproterenol caused a significant increase of the Bmax value of [3H]clonidine binding sites at both days 7 and 70, without changing the Kd. Scatchard analysis of [3H]clonidine binding to adult synaptic membranes which was examined by using a wide range of [3H]clonidine concentration (0.05-15 nM), showed that the Bmax in only high-affinity binding sites was 4-fold increased by pretreatment of synaptic membranes with isoproterenol 200 microM. In contrast, the Bmax of [3H]DHA binding sites was significantly reduced by isoproterenol at 7 and 70 days. These results suggest that the possible interrelationship between beta- and alpha 2-adrenoceptors which exists in synaptic membranes, matures by day 7 in the cerebral cortex of rats.
D000526:Alprenolol / Q000031:analogs & derivatives*; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D003000:Clonidine / Q000378:metabolism*; D004082:Dihydroalprenolol / Q000378:metabolism*; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D051381:Rats / Q000378:metabolism*; D011919:Rats, Inbred Strains; D014316:Tritium
D014316:Tritium; D004082:Dihydroalprenolol; D000526:Alprenolol; D007545:Isoproterenol; D003000:Clonidine