The beta 1- and beta 2-adrenoceptor subtypes in cultured rat inner medullary collecting duct cells.
We investigated beta-adrenoceptor subtype(s) expressed in cultured rat inner medullary collecting duct (IMCD) cells. In radioligand binding assay, [125I]iodocyanopindolol bound to IMCD cell membranes, representing a single class of binding sites (dissociation constant = 96.1 pM, maximum binding capacity = 18.2 fmol/mg protein, n = 8). In competition studies, ICI-89406 (beta 1-antagonist) and ICI-118551 (beta 2-antagonist) bound with high affinity, fitting a two-site model. Isoproterenol increased intracellular adenosine 3',5'-cyclic monophosphate (cAMP) accumulation (half-maximal effective concentration = 200 nM). Propranolol completely inhibited isoproterenol-induced cAMP accumulation [half-maximal inhibitory concentration (IC50) = 270 nM]. ICI-89406 and ICI-118551 inhibited cAMP accumulation by 50% (IC50 = 1.5 microM and 1.7 microM, respectively). The combined addition of ICI-89406 and ICI-118551 resulted in a curve indistinguishable from that of propranolol. The beta 1- and beta 2-adrenoceptor mRNAs have been demonstrated using reverse transcription-polymerase chain reaction. In initial and terminal IMCD cells, propranolol (3 microM) inhibited isoproterenol-stimulated cAMP accumulation by 80%, whereas ICI-89406 (3 microM) and ICI-118551 (3 microM) resulted in only partial inhibition (50%). We conclude that both beta 1- and beta 2-adrenoceptors are expressed in initial and terminal IMCD cells in primary culture.
Yasuda
G
G
Second Department of Internal Medicine, Yokohama City University School of Medicine, Japan.
Sun
L
L
Lee
H C
HC
Umemura
S
S
Jeffries
W B
WB
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive; D015139:Blotting, Southern; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000494:pharmacology; D007679:Kidney Medulla; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D008297:Male; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011869:Radioligand Assay; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D014018:Tissue Distribution; D014158:Transcription, Genetic
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D010869:Pindolol; D000242:Cyclic AMP; D007545:Isoproterenol