Relaxing effect of pharmacologic interventions increasing cAMP in rat heart

1981 ◽  
Vol 240 (4) ◽  
pp. H441-H447
Author(s):  
L. Vittone ◽  
A. Grassi ◽  
L. Chiappe ◽  
M. Argel ◽  
H. E. Cingolani
Keyword(s):  
Protein Kinase ◽  
Rat Heart ◽  
Kinase Activity ◽  
Isolated Rat Heart ◽  
Protein Kinase Activity ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
High Calcium ◽  
Dependent Protein ◽  
Camp Levels

The relationship between cAMP and relaxation was studied in the isolated rat heart beating at constant rate and perfused at constant coronary flow. After treatment during 1 min with different positive inotropic interventions, cyclic nucleotide levels (cAMP and cGMP) and cAMP-dependent protein kinase activity were determined in heart homogenates. Glucagon, norepinephrine, and isoproterenol increased cAMP from 0.503 +/- 0.025 pmol/mg wet wt to 1.051 +/- 0.099, 0.900 +/- 0.064, and 0.982 +/- 0.138, respectively. Simultaneously glucagon, norepinephrine, and isoproterenol increased cAMP-dependent protein kinase activity ratio from 0.21 +/- 0.02 to 0.45 +/- 0.04, 0.33 +/- 0.02, and 0.34 +/- 0.02, respectively. The ratio between maximal velocities of contraction and relaxation (+T/-T) was significantly decreased by these interventions, whereas time to peak tension (TTP) was shortened by norepinephrine and isoproterenol. High calcium, ouabain, and paired stimulation did not affect cAMP levels, TTP, or +T/-T. A striking correlation was found between cAMP-dependent protein kinase activity and relaxation induces, i.e., TTP, -T, or +T/-T (r = +/- 0.7 to -0.9). Results suggest that inotropic interventions increasing cAMP levels might be primarily affecting intracellular mechanisms causing relaxation.

Analytical subcellular distribution of cAMP-dependent protein kinase activity in bull sperm

1984 ◽  
Vol 10 (4) ◽  
pp. 433-444 ◽  
Author(s):  
Claude C. Pariset ◽  
Jacqueline S. Weinman ◽  
Francoise T. Escaig ◽  
Michele Y. Guyot ◽  
Francine C. Iftode ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Subcellular Distribution ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Bull Sperm

Involvement of cAMP-dependent protein kinase in the regulation of heart contractile force. II

1979 ◽  
Vol 236 (1) ◽  
pp. H84-H91
Author(s):  
S. L. Keely ◽  
A. Eiring
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Activity Ratio ◽  
Contractile Force ◽  
Protein Kinase Activity ◽  
Phosphorylase Activity ◽  
Dependent Protein Kinase ◽  
Guinea Pig Heart ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

The effects of histamine on heart cAMP-dependent protein kinase activity, cAMP levels, phosphorylase activity, and contractile force was investigated in the perfused guinea pig heart. To accurately determine the protein kinase activity ratio in guinea pig heart, it was necessary to measure kinase activity in whole homogenates immediately after homogenization of the tissue. Histamine produced a rapid dose-dependent increase in cAMP and the protein kinase activity ratio followed by increased in contractile force and phosphorylase activity. There was a good correlation between the degree of protein kinase activation and the increase in phosphorylase and force. The beta-adrenergic blocking agent propranolol did not reduce the effects of histamine, but metiamide, a potent H2-receptor antagonist, greatly attenuated all the effects of histamine. The data support the hypothesis that increases in heart cAMP-dependent protein kinase activity produce corresponding increases in contractile force and phosphorylase activity.

scholarly journals Imaging of cAMP-dependent protein kinase activity in living neural cells using a novel fluorescent substrate

FEBS Letters ◽  
1997 ◽  
Vol 414 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Hideyoshi Higashi ◽  
Kazuki Sato ◽  
Atsuko Ohtake ◽  
Akira Omori ◽  
Sachiyo Yoshida ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Neural Cells ◽  
Dependent Protein Kinase ◽  
Fluorescent Substrate ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

Biochemical changes accompanying enhanced cardiac contractility by ionophore A23187

1985 ◽  
Vol 249 (6) ◽  
pp. H1204-H1210 ◽  
Author(s):  
J. J. Murray ◽  
P. W. Reed ◽  
J. G. Dobson
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Ionophore A23187 ◽  
Phosphorylase Activity ◽  
Dependent Protein Kinase ◽  
Camp Content ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

We have reported that the divalent cation ionophore A23187, like the beta-adrenergic agonist isoproterenol, increased the force of contraction and rate of relaxation and shortened the duration of contraction of papillary muscles isolated from guinea pigs. A23187 produced a fall in resting tension and decreased the contracture tension of K +/- depolarized muscles, as did isoproterenol. In the present studies, isoproterenol produced a concentration-dependent, rapid, and sustained increase in the cyclic AMP (cAMP) content of papillary muscle. In contrast, A23187 had no detectable effect on cAMP levels, even in the presence of the phosphodiesterase inhibitor, papaverine. Neither drug, at concentrations maximal for contractile effects, altered cyclic GMP (cGMP). Isoproterenol increased the cAMP-dependent protein kinase activity ratio, whereas A23187 did not change the activity of this enzyme. However, both A23187 and isoproterenol produced a concentration-dependent increase in phosphorylase activity. Concentrations of A23187 or isoproterenol that enhanced contractility maximally increased the alkali-labile phosphate (by ca. 35%) but were without effect on the acid-labile, alkali-stable phosphate in the total acid precipitable protein. Contractile effects of isoproterenol, which reflect activated Ca2+ uptake, and the increase in phosphorylase activity produced by this agent are believed to be due to an increase in cAMP with subsequent activation of cAMP-dependent protein kinases and phosphorylation of proteins. A23187 may produce similar contractile effects without an increase in cAMP or cAMP-dependent protein kinase activity by activating other protein kinases and/or inhibiting phosphoprotein phosphatases, most likely by its effects on intracellular calcium.

Protein kinase regulation of cardiac phosphorylase activity and contractility

1978 ◽  
Vol 234 (5) ◽  
pp. H638-H645 ◽  
Author(s):  
J. G. Dobson
Keyword(s):  
Protein Kinase ◽  
Time Course ◽  
Kinase Activity ◽  
Vena Cava ◽  
Left Ventricular ◽  
Protein Kinase Activity ◽  
Phosphorylase Activity ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

The relationship between cAMP-dependent protein kinase activity and epinephrine-produced activation of phosphorylase and increase in contractility was investigated in the intact working rat heart. Epinephrine was administered as a bolus into the superior vena cava of open-chest preparations and the hearts were rapidly frozen. cAMP increased within 5 s and returned to control within 20-30 s. Protein kinase and phosphorylase kinase activity ratios increased transiently with the same time course as that for cAMP. The phosphorylase activity ratio and the rate of left ventricular pressure development increased maximally within 15 s and returned to control in 30-60 s. Continuous infusion of epinephrine caused a sustained elevation of the protein kinase. Free catalytic protein kinase activity increased proportionately with the dose of epinephrine. The beta-adrenergic blocking agent, practolol, had no effect on the basal levels of the five parameters studied, but did prevent the epinephrine-produced increases. The results suggest that the time course of cAMP-dependent protein kinase activation is appropriate if this enzyme is to play a role in the catecholamine-induced increase in both glycogenolysis and contractility in the in vivo heart.

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