A. Yatani et al., STABLE EXPRESSION AND COUPLING OF CARDIAC L-TYPE CA2-ADRENOCEPTORS( CHANNELS WITH BETA(1)), Circulation research, 76(3), 1995, pp. 335-342
A number of neurotransmitters modulate cardiac dihydropyridine-sensiti
ve L-type Ca2+ channels through several homologous G protein-coupled r
eceptors. Previous studies that have examined receptor-Ca2+ channel in
teractions have suffered because of the coexpression of various recept
or subtypes in native cells. To study the functional coupling of a par
ticular receptor subtype to these channels, rabbit cardiac Ca2+ channe
l alpha(1) and skeletal beta and (alpha(2)/delta subunits were stably
expressed in baby hamster kidney cells. In this stable cell line, Ca2 channels remained at high levels (>1000 fmol/mg protein, or 2700 chan
nels per cell) over extended times. The expressed recombinant Ca2+ cha
nnels displayed the voltage dependence of activation and inactivation,
unitary conductance, and pharmacology characteristic of native cardia
c L-type Ca2+ channels. Subsequent coexpression of the beta(1)-adrenoc
eptors (150 to 300 fmol/mg protein) with the Ca2+ channels resulted in
cell responsiveness to the extracellular application of isoproterenol
. These results indicate that heterogeneous expression in mammalian ce
lls provides a useful system for studying both biophysical analysis of
Ca2+ channel properties and receptor-coupled regulatory processes.