| Abstract: | We have measured alprenolol binding and cyclic AMP production in erythroid cells taken from chick embryos incubated from 8 days to hatching and in cells from the adult. Beta-adrenergic receptor number and affinity measured by alprenolol binding are essentially unchanged in red cell membranes prepared from 8- through 17-day embryos. Receptor number was found to be half as much in the adult. Erythroid cells from embryos of all ages studied show stimulation of cyclic AMP production when incubated with epinephrine, and most of the cyclic AMP produced remains intracellular. Inasmuch as the cells from younger embryos can in fact produce cyclic AMP, the previously-reported lack of epinephrine sensitivity of cation transport in the red cells of younger embryos (Wacholtz et al., 1978) cannot be attributed to the lack of functional receptors or to an impairment of cyclic AMP production. |
