Adenylate cyclase uncoupled β-adrenergic receptors in salamander proximal tubules

1990 ◽  
Vol 68 (7) ◽  
pp. 863-869 ◽  
Author(s):  
Nikolas S. Morgunov ◽  
David J. Hirsch
Keyword(s):  
Adenylate Cyclase ◽  
Proximal Tubule ◽  
Adrenergic Receptors ◽  
Proximal Tubules ◽  
Ambystoma Tigrinum ◽  
Adenylate Cyclase System ◽  
Binding Studies ◽  
Binding Characteristics ◽  
Cgp 12177 ◽  
Β Adrenergic Receptors

The isolated perfused proximal tubule of the neotenic salamander Ambystoma tigrinum responds with either a hyperpolarization or depolarization of both the basolateral cell membrane and transepithelial potentials following the addition of 10−5 M isoproterenol to the bath superfusate. Both responses were blocked by 10−6 M propranolol but neither response was mimicked by 10−4 M cAMP. β-Adrenergic binding studies of individual microdissected proximal tubules using (−)-[3H]CGP-12177 as a hydrophyllic radioligand and (±)-timolol (0.1 mM) as the displacer drug revealed two distinct populations of proximal tubules possessing either low (KD = 153.8 nM; Bmax = 110.2 fM/mm) or high affinity (KD = 12.0 nM; Bmax = 3.9 fM/mm) binding characteristics. Competition studies indicated that the bound (−)-[3H]CGP-12177 behaved as a typical β-adrenergic ligand, being displaced by (−)-isoproterenol but not by (+)-isoproterenol or (−)phenylephrine. However, neither appeared to be coupled to the adenylate cyclase system. These data suggest the presence of functional β-adrenergic receptors that do not appear to be coupled to the adenylate cyclase system.Key words: proximal tubule, β-receptors, adenylate cyclase.

Beta-adrenergic receptor function in rat proximal tubule epithelial cells in culture

1995 ◽  
Vol 268 (4) ◽  
pp. F553-F560 ◽  
Author(s):  
A. S. Hanson ◽  
S. L. Linas
Keyword(s):  
Epithelial Cells ◽  
Adenylate Cyclase ◽  
Proximal Tubule ◽  
Adrenergic Receptors ◽  
Proximal Tubules ◽  
Sodium Reabsorption ◽  
Scatchard Analysis ◽  
Beta Adrenergic ◽  
Alpha Adrenergic Receptors ◽  
And Function

The adrenergic system is important in regulating proximal tubule sodium reabsorption. Although alpha-adrenergic receptors have been identified in proximal tubules, the presence and function of beta-adrenergic receptors (BAR) in proximal tubules is less certain. The purpose of our study was to determine whether functional BAR are present on apical or basolateral surfaces of proximal tubule epithelial cells (PTEC) of rat kidney. We specifically focused on BAR coupling to adenylate cyclase and on differences between requirements for apical and basolateral receptor coupling to adenylate cyclase. To determine BAR expression and function, primary cultures of rat PTECs were grown on permeable supports. Scatchard analysis of 125I-labeled cyanopindolol binding revealed a single class of receptors on both apical and basolateral surfaces. Apical isoproterenol (ISO) resulted in time- and concentration-dependent increases in adenosine 3',5'-cyclic monophosphate (cAMP) that were 50% of responses after basolateral ISO. Apical BAR-cAMP coupling was mediated by B1-adrenergic receptors (B1AR), since apical cAMP responses were abrogated with apical (but not basolateral) B1 but not B2 antagonists. Apical B1AR required endocytosis prior to adenylate cyclase activation, since increases in cAMP were prevented by phenylarsine oxide or colchicine. B1AR-adenylate cyclase coupling was independent of intra- or extracellular calcium, cyclooxygenase metabolites, and protein kinase C (PKC) and dependent on Gs guanine nucleotide regulatory protein. Prolonged exposure to ISO resulted in time- and concentration-dependent homologous desensitization of cAMP responses. Desensitization was independent of receptor sequestration, PKA, or PKC. We conclude the following: B1AR are present on both apical and basolateral surfaces of rat PTECs.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta-adrenoceptor adenylate cyclase system adaptation to physical training in rat ventricular tissue

1991 ◽  
Vol 70 (4) ◽  
pp. 1633-1638 ◽  
Author(s):  
G. Plourde ◽  
S. Rousseau-Migneron ◽  
A. Nadeau
Keyword(s):  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Adenylate Cyclase System ◽  
Beta Adrenergic Receptors ◽  
Binding Studies ◽  
Beta Adrenergic ◽  
Beta Adrenoceptor ◽  
Ventricular Tissue ◽  
System Adaptation

The beta-adrenergic receptor adenylate cyclase system of ventricular tissue was evaluated in a group of rats submitted to a progressive 10-wk running program on a treadmill and compared with that in a group of rats maintained sedentary during the same period. Adequate training was confirmed by a 46% increase in the gastrocnemius isocitrate dehydrogenase activity in the trained group [1.50 +/- 0.04 vs. 1.03 +/- 0.06 (SE) pmol.g-1.min-1; P less than 0.01). Binding studies with [125I]iodocyanopindolol showed a 13% reduction in the density of beta-adrenergic receptors in trained rats (42.6 +/- 2.1 vs. 49.0 +/- 2.1 fmol/mg; P less than 0.05) without any significant modification in the dissociation constant. The amount of [125I]iodocyanopindolol bound to beta-adrenoceptors in the high-affinity state was reduced by 16.6% in trained rats (12.5 +/- 0.9 vs. 15.0 +/- 0.5 fmol/mg; P less than 0.05) without any significant changes for those in the low-affinity state, indicating a decrease in the coupling between the beta-adrenergic receptors and the guanine stimulatory binding protein. Furthermore, although the basal and sodium fluoride-stimulated adenylate cyclase activities were similar in the two groups of rats, the response of adenylate cyclase maximally stimulated by 10(-5) M isoproterenol was reduced by 16% in trained rats (29.7 +/- 1.4 vs. 35.3 +/- 1.3 pmol.mg-1.min-1; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha- and beta-adrenergic receptors in proximal tubules of rat kidney

1987 ◽  
Vol 253 (5) ◽  
pp. F848-F856 ◽  
Author(s):  
P. R. Sundaresan ◽  
T. L. Fortin ◽  
S. L. Kelvie
Keyword(s):  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Rat Kidney ◽  
Proximal Tubules ◽  
Beta Adrenergic Receptors ◽  
Binding Studies ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Proximal Tubular

Proximal tubules were isolated from the rat kidney by collagenase digestion of the cortical tissue followed by Percoll gradient centrifugation. Microscopic and hormone-stimulated adenylate cyclase activity studies proved the purity of the preparation. [3H]Prazosin, [3H]rauwolscine, and [125I]iodocyanopindolol were used to identify and quantitate respectively the alpha 1-, alpha 2- and beta-adrenergic receptors. Proximal tubular (F4) particulate fraction was compared against other cortical nephron segment (F1, F2) fractions and the total collagenase-digested cortex particulate suspension (Ft). Proximal tubules were enriched in alpha 1- and alpha 2-adrenergic receptors compared with Ft (alpha 1-receptor, 100.4 +/- 4.5 vs. 87.4 +/- 4.9; alpha 2-receptor, 250 +/- 16.2 vs. 185.1 +/- 12 fmol/mg protein). The fractions enriched in glomeruli and distal tubular segments (F1, F2) had relatively low concentrations of alpha 1- and alpha 2-adrenergic receptors. In contrast, beta-adrenergic receptor concentration in the proximal tubules was approximately 25% of that in the Ft fraction and approximately 10% of that in the F1 fraction. Isoproterenol-stimulated adenylate cyclase activities in the different fractions corroborated well with the pattern suggested by the [125I]iodocyanopindolol binding studies. Our results suggest that whole-cortex preparation radioligand binding studies may reflect proximal tubular alpha 1- and alpha 2-adrenergic receptor changes quite well. They may, however, miss or give erroneous impressions about beta-adrenergic receptor changes occurring in different cortical nephron segments.

β-Adrenergic Receptors in the Rat Mammary Gland during Pregnancy and Lactation: Characterization, Distribution, and Coupling to Adenylate Cyclase

Endocrinology ◽  
1990 ◽  
Vol 126 (1) ◽  
pp. 565-574 ◽  
Author(s):  
BIANCA MARCHETTI ◽  
MICHEL-A FORTIER ◽  
PATRICK POYET ◽  
NICOLLE FOLLEA ◽  
GEORGES PELLETIER ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Pregnancy And Lactation ◽  
Rat Mammary Gland ◽  
Β Adrenergic Receptors

Regulation of Adenylate Cyclase Coupled β-Adrenergic Receptors

1976 ◽  
pp. 597-630
Author(s):  
ROBERT J. LEFKOWITZ ◽  
CHHABIRANI MUKHERJEE ◽  
LEEE. LIMBIRD ◽  
MARCG. CARON ◽  
LEWIST. WILLIAMS ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Β Adrenergic Receptors

scholarly journals Adrenergic and Cholinergic Receptors of Cerebral Microvessels

1981 ◽  
Vol 1 (3) ◽  
pp. 329-338 ◽  
Author(s):  
Sami I. Harik ◽  
Virendra K. Sharma ◽  
John R. Wetherbee ◽  
Robert H. Warren ◽  
Shailesh P. Banerjee
Keyword(s):  
Adrenergic Receptors ◽  
Specific Binding ◽  
Cholinergic Receptors ◽  
Biologically Active ◽  
Adrenergic Agonists ◽  
Muscarinic Cholinergic Receptors ◽  
Cerebral Microvessels ◽  
Binding Characteristics ◽  
Muscarinic Cholinergic ◽  
Β Adrenergic Receptors

The presence of α- and β-adrenergic and muscarinic cholinergic receptors in cerebral microvessels of the rat and pig was assessed by ligand binding techniques. The results demonstrate the presence of specific binding to α2- and β-adrenergic receptors but no appreciable specific binding to α1-adrenergic or muscarinic cholinergic receptors. β-Adrenergic receptors of pig cerebral microvessels are similar to those of the brain and other organs in their binding characteristics to the tritiated ligand and in their stereospecificity of binding to the biologically active isomers of β-adrenergic agonists. Further evidence derived from the differential potency of binding displacement by the various β-adrenergic agonists and selective β1- and β2-adrenergic antagonists indicates that β-adrenergic receptors of pig cerebral microvessels are mostly of the β2-subtype.

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