Expression of the diverse subtypes of inositol 1,4,5-trisphosphate (In
sP(3)) receptor (IP(3)R) was examined in rat adrenal glomerulosa cells
. The polymerase chain reaction products were characterized by means o
f DNA sequencing and/or restriction enzyme mapping. The predominant su
btype expressed is IP(3)R-1; its alternatively spliced variants contai
ning and lacking segment SZ are present in comparable amounts, The exp
ression level of IP(3)R-2 is about a quarter that of IP(3)R-1, whereas
IP(3)R-3 is expressed at a very low level. Sodium depletion, a chroni
c physiological stimulus of glomerulosa cells, failed to influence the
expression of IP(3)R-1, as measured by competitive polymerase chain r
eaction, and failed to modify the ratio of the different receptor subt
ypes, as studied with restriction enzyme mapping.