Beta-adrenergic-mediated Cl secretion: evidence for additional non-cAMP-dependent pathway of effect

1990 ◽  
Vol 259 (6) ◽  
pp. L426-L431 ◽  
Author(s):  
R. D. Feldman ◽  
A. Brotherton ◽  
M. J. Welsh
Keyword(s):  
Protein Kinase ◽  
Adenylyl Cyclase ◽  
Adrenergic Receptor ◽  
Chloride Secretion ◽  
Intrinsic Sympathomimetic Activity ◽  
Camp Accumulation ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Kinase A ◽  
Stimulation Of

It has been suggested that beta-adrenergic receptor antagonists with intrinsic sympathomimetic activity, like pindolol, are weak partial agonists for beta-adrenergic-stimulated adenylyl cyclase activation. To evaluate this possibility, beta-adrenergic-mediated chloride secretion was studied in tracheal epithelial cells maintained in primary culture. Pindolol caused a dose-dependent increase in chloride secretion with a half-maximal effective concentration of 91 pM to a maximum that was 30 +/- 3% that of isoproterenol. Pindolol-induced chloride secretion was antagonized by the beta-adrenergic antagonist nadolol. However, in contrast to isoproterenol, pindolol did not stimulate adenosine 3',5'-cyclic monophosphate (cAMP) accumulation, adenylyl cyclase activity, or protein kinase A activation. Further studies examined the coupling of beta-adrenergic stimulation of cAMP accumulation to beta-adrenergic stimulation of chloride secretion. Coincubation of cells with the phosphodiesterase inhibitor RA233 increased maximal isoproterenol-stimulated cAMP accumulation eightfold but did not significantly increase the potency or maximal effect of isoproterenol for chloride secretion. It is clear that beta-adrenergic-stimulated elevations in cAMP mediate chloride secretion. These studies also demonstrate that pindolol, a drug with intrinsic sympathomimetic activity, mediates a beta-adrenergic receptor-specific increase in chloride secretion without increasing adenylyl cyclase nor protein kinase A activities. Thus intrinsic sympathomimetic activity may represent a non-cAMP-dependent mechanism of beta-adrenergic effect.

TGF-beta 1 modulates beta-adrenergic receptor number and function in cultured human tracheal smooth muscle cells

1994 ◽  
Vol 266 (2) ◽  
pp. L187-L191 ◽  
Author(s):  
M. Nogami ◽  
D. J. Romberger ◽  
S. I. Rennard ◽  
M. L. Toews
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Adenylyl Cyclase ◽  
Adrenergic Receptor ◽  
Muscle Cells ◽  
Camp Accumulation ◽  
Tgf Beta ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Receptor Number

Pretreatment of cultured human tracheal smooth muscle cells with transforming growth factor-beta 1 (TGF-beta 1) decreased adenosine 3',5'-cyclic monophosphate (cAMP) accumulation by intact cells stimulated with the beta-adrenergic agonist isoproterenol. The maximal inhibition of isoproterenol-stimulated cAMP accumulation by TGF-beta 1 was 31 +/- 3%, and the mean effective concentration (EC50) of TGF-beta 1 was approximately 1.5 pM. TGF-beta 1 decreased the maximal response to isoproterenol but did not change the EC50 value of isoproterenol. TGF-beta 1 did not change cAMP accumulation stimulated by forskolin. TGF-beta 1 pretreatment decreased isoproterenol-stimulated adenylyl cyclase activity measured in broken cell preparations, but did not change the fluoride-stimulated adenylyl cyclase activity. Together these results suggest that the TGF-beta 1 effect is not by direct inhibition of adenylyl cyclase or by decreased activity of the stimulatory GTP-binding protein. Saturation binding experiments with the beta-adrenergic receptor radioligand [125I]iodopindolol showed that TGF-beta 1 pretreatment decreased the beta-adrenergic receptor number. The protein synthesis inhibitor cycloheximide abolished the effect of TGF-beta 1 on both cAMP accumulation and on beta-adrenergic receptor number, indicating that protein synthesis is involved. These results suggest that TGF-beta 1 in the lung could play a role in changing the responsiveness of airway smooth muscle cells to endogenous catecholamines and to beta-adrenergic agonists used in therapy.

scholarly journals Regulation of Cardiac L-Type Ca 2+ Channel Ca V 1.2 Via the β-Adrenergic-cAMP-Protein Kinase A Pathway

2013 ◽  
Vol 113 (5) ◽  
pp. 617-631 ◽  
Author(s):  
Sharon Weiss ◽  
Shimrit Oz ◽  
Adva Benmocha ◽  
Nathan Dascal
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Adrenergic Receptor ◽  
Transgenic Animals ◽  
Receptor Activation ◽  
Model Systems ◽  
Adrenergic Stimulation ◽  
New Findings ◽  
Kinase A

In the heart, adrenergic stimulation activates the β-adrenergic receptors coupled to the heterotrimeric stimulatory G s protein, followed by subsequent activation of adenylyl cyclase, elevation of cyclic AMP levels, and protein kinase A (PKA) activation. One of the main targets for PKA modulation is the cardiac L-type Ca 2+ channel (Ca V 1.2) located in the plasma membrane and along the T-tubules, which mediates Ca 2+ entry into cardiomyocytes. β-Adrenergic receptor activation increases the Ca 2+ current via Ca V 1.2 channels and is responsible for the positive ionotropic effect of adrenergic stimulation. Despite decades of research, the molecular mechanism underlying this modulation has not been fully resolved. On the contrary, initial reports of identification of key components in this modulation were later refuted using advanced model systems, especially transgenic animals. Some of the cardinal debated issues include details of specific subunits and residues in Ca V 1.2 phosphorylated by PKA, the nature, extent, and role of post-translational processing of Ca V 1.2, and the role of auxiliary proteins (such as A kinase anchoring proteins) involved in PKA regulation. In addition, the previously proposed crucial role of PKA in modulation of unstimulated Ca 2+ current in the absence of β-adrenergic receptor stimulation and in voltage-dependent facilitation of Ca V 1.2 remains uncertain. Full reconstitution of the β-adrenergic receptor signaling pathway in heterologous expression systems remains an unmet challenge. This review summarizes the past and new findings, the mechanisms proposed and later proven, rejected or disputed, and emphasizes the essential issues that remain unresolved.

β-Adrenergic and antiadrenergic modulation of cardiac adenylyl cyclase is influenced by phosphorylation

2003 ◽  
Vol 285 (4) ◽  
pp. H1471-H1478 ◽  
Author(s):  
James G. Dobson ◽  
Lynne G. Shea ◽  
Richard A. Fenton
Keyword(s):  
Protein Kinase ◽  
Adenylyl Cyclase ◽  
Adrenergic Receptor ◽  
Kinase Inhibitor ◽  
Cyclase Activity ◽  
Adenylyl Cyclase Activity ◽  
Protein Substrates ◽  
Membrane Phosphorylation ◽  
Mediated Reduction ◽  
Kinase A

Adenosine protects the myocardium of the heart by exerting an antiadrenergic action via the adenosine A1 receptor (A1R). Because β1-adrenergic receptor (β1R) stimulation elicits myocardial protein phosphorylation, the present study investigated whether protein kinase A (PKA) catalyzed rat heart ventricular membrane phosphorylation affects the β1R adrenergic and A1R adenosinergic actions on adenylyl cyclase activity. Membranes were either phosphorylated with PKA in the absence/presence of a protein kinase inhibitor (PKI) or dephosphorylated with alkaline phosphatase (AP) and assayed for adenylyl cyclase activity (AC) in the presence of the β1R agonist isoproterenol (ISO) and/or the A1R agonist 2-chloro- N6-cyclopentyladenosine (CCPA). 32P incorporation into the protein substrates of 140–120, 43, and 29 kDa with PKA increased both the ISO-elicited activation of AC by 51–54% and the A1R-mediated reduction of the ISO-induced increase in AC by 29–50%, thereby yielding a total antiadrenergic effect of ∼78%. These effects of PKA were prevented by PKI. AP reduced the ISO-induced increase in AC and eliminated the antiadrenergic effect of CCPA. Immunoprecipitation of the solubilized membrane adenylyl cyclase with the use of a polyclonal adenylyl cyclase VI antibody indicated that the enzyme is phosphorylated by PKA. These results indicate that the cardioprotective effect of adenosine afforded by its antiadrenergic action is facilitated by cardiac membrane phosphorylation.

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