Pharmacological properties of the norepinephrine-induced depolarization of astrocytes in primary culture: evidence for the involvement of an α1-adrenergic receptor

The membrane potentials of astrocytes in primary cultures prepared from neonatal rat cerebral cortices were depolarized by (−)-norepinephrine. The average first response to 10⁻⁵ M (−)-norepinephrine was 24 mV from an average resting potential of −68 mV, and the average for the second response was 14 mV. Thus this process showed marked desensitization. The response was attributed to an activation of an α₁-receptor since it was about 1000 times more sensitive to inhibition by prazosin than to yohimbine or idazoxan. In addition, depolarization was seen to the application of 10⁻⁵ M phenylephrine.     

Absence of predictable phenotypic expression in proximal 15q duplications

We describe ten individuals with an insertional duplication 15q12----q13. Phenotypic analysis of these individuals and 15 previously reported cases of proximal 15q duplications fails to show any consistent clinical manifestations. It appears that a duplication of this region is phenotypically silent.