C. Faure et al., EXPRESSION OF ALPHA(1)-ADRENOCEPTOR SUBTYPES IN RAT-TISSUES - IMPLICATIONS FOR ALPHA(1)-ADRENOCEPTOR CLASSIFICATION, European journal of pharmacology. Molecular pharmacology section, 268(2), 1994, pp. 141-149
We report here the mapping of the mRNA distribution of three different
alpha(1)-adrenoceptor subtypes (alpha(1b), alpha(1c) and alpha(1d)) i
n various rat tissues. cDNA fragments covering the region from the fif
th to seventh putative transmembrane spanning domains of these three a
lpha(1)-adrenoceptor subtypes were generated from rat hippocampus usin
g reverse transcription coupled to polymerase chain reaction (PCR). Th
ese three alpha(1)-adrenoceptor cloned cDNA fragments were then used a
s subtype-selective cDNA probes in Northern blot analysis. Of the thre
e specific DNA probes only the rat alpha(1b)-adrenoceptor probe hybrid
ized to mRNA of rat liver. The rat alpha(1c)-adrenoceptor probe hybrid
ized to a mRNA species of 3.7 kb in tissues that have been reported to
contain the classical pharmacologically-defined alpha(1A)-adrenocepto
r such as hippocampus, vas deferens, lung and salivary gland. Also, a
major mRNA transcript of 2.7 kb was detected in hippocampus, vas defer
ens and lung, using the rat alpha(1d)-adrenoceptor probe. In addition,
pharmacological characterization of [H-3]prazosin binding to three st
ably transfected mammalian cell-lines expressing one of the three alph
a(1)-adrenoceptor subtypes cloned to date (namely, alpha(1b)- of the h
amster smooth muscle DDT1-MF2 cell-line, the bovine brain alpha(1c) -
and the rat cerebral cortical alpha(1d)-adrenoceptors) was performed.
Of the three cloned alpha(1)-adrenoceptor subtypes the alpha(1c)-adren
oceptor showed a similar pharmacological profile to that of the classi
cal alpha(1A)-adrenoceptor of rat salivary gland. Our data on the phar
macological profile and expression pattern of the alpha(1c)-adrenocept
or indicate, in contrast to earlier claims (Schwinn et al., J. Biol. C
hem. 265, 1990), that this subtype is in fact the classical pharmacolo
gically-defined alpha(1A)-adrenoceptor subtype.