| Abstract: | Age dependence of alpha 1-adrenergic receptor number on hepatocytes of chickens was determined by incubation of liver cell membranes from chickens of different ages with 3H-prazosin. We showed, that there is a continuous and significant rise of alpha 1-adrenergic binding sites with increasing age of the chickens from 226 +/- 22 fmol/mg protein at the age of up to 4 weeks to 628 +/- 34 fmol/mg protein in laying hens. Changes in receptor affinity could not be registered. The KD-values ranged insignificantly from 0.34 +/- 0.03 nM to 0.50 +/- 0.06 nM in the different ages of chickens and amounted to 0.44 +/- 0.02 nM averagely. The classification of the binding sites for 3H-prazosin to the alpha 1B-subtype could be caused by the high sensitivity to chlorethylclonidine and by the low affinity for alpha A-adrenergic antagonists. |
