We find similar number of α1-adrenergic receptors in fetal mouse hearts of 15–20 day gestational age as compared to adult mouse hearts, and a significantly greater number of α1-adrenoceptors in the early neonate (7–21 days) hearts. Cardiac norepinephrine (NE) concentrations were extremely low inthe fetus and increased continuously after birth to reach adult levels at about 21 days of age. Te cardiac α1-adrenergic receptors prior to the development of a presynaptic component (NE) and show a dramatic increase in density without a change in affinity in the early neonate which then decrease with innervation.
- Cardiac α-adrenergic receptor
- Norepinephrine levels
- [H]WB4101 binding
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