Na+-dependence of 45Ca2+ uptake in adult rat isolated cardiac cells

1982 ◽  
Vol 721 (2) ◽  
pp. 144-157 ◽  
Author(s):  
Michel Desilets ◽  
Magda Horackova
Keyword(s):  
Cardiac Cells ◽  
Adult Rat ◽  
Isolated Cardiac Cells

Effect of quinidine on Na-dependent 45Ca transport in isolated adult cardiac cells

1984 ◽  
Vol 62 (5) ◽  
pp. 575-580 ◽  
Author(s):  
Michel Désilets ◽  
Magda Horackova
Keyword(s):  
Specific Inhibitor ◽  
Cellular Membrane ◽  
Cardiac Cells ◽  
Adult Rat ◽  
Intracellular Compartments ◽  
Intracellular Ca ◽  
Isolated Cardiac Cells ◽  
High Concentrations ◽  
Rat Cardiac Myocytes ◽  
Isolated Rat

The effects of quinidine on Na+-dependent Ca2+ transport in adult rat isolated cardiac cells have been studied by measuring 45Ca2+ uptake and efflux at various external Na+ concentrations ([Na +]o). Quinidine (>50 μM) appreciably inhibited the Ca2+ uptake induced by lowering [Na+]o but had little effect on the Ca2+ efflux. The conclusion that the apparent inhibition of the Na+-dependent Ca2+ uptake was probably due to a general inhibition of the Ca2+ entry through cellular membrane and, at high concentrations, into the intracellular compartments rests on the observations that: (i) in non-steady-state conditions, the fraction of Ca2+ uptake inhibited by quinidine was independent of [Na+]o; (ii) lidocaine, which is known to have effects on membrane electrical activity and Na+ permeability similar to those of quinidine, did not affect the Ca2+ movements; and (iii) when incubated in low [Na+]o, quinidine (>0.2 mM) caused an irreversible contracture of a fraction of the myocyte population, even if about 50% of the Ca2+ uptake induced by lowering [Na+]o was inhibited. The results of this study therefore suggest that quinidine cannot be considered a specific inhibitor of the Na+–Ca2+ exchange in isolated rat cardiac myocytes and indicate the importance of quinidine's effects on intracellular Ca2+ regulation in cardiac muscle.

Electrophysiology of the Sodium-Potassium-ATPase in Cardiac Cells

2001 ◽  
Vol 81 (4) ◽  
pp. 1791-1826 ◽  
Author(s):  
Helfried Günther Glitsch
Keyword(s):  
Cell Membrane ◽  
Potential Gradient ◽  
Outward Current ◽  
Pump Current ◽  
Cardiac Cells ◽  
Animal Cells ◽  
Excitable Cells ◽  
Extracellular Medium ◽  
Enzymatic Isolation ◽  
Isolated Cardiac Cells

Like several other ion transporters, the Na+-K+ pump of animal cells is electrogenic. The pump generates the pump current I p. Under physiological conditions, I p is an outward current. It can be measured by electrophysiological methods. These methods permit the study of characteristics of the Na+-K+ pump in its physiological environment, i.e., in the cell membrane. The cell membrane, across which a potential gradient exists, separates the cytosol and extracellular medium, which have distinctly different ionic compositions. The introduction of the patch-clamp techniques and the enzymatic isolation of cells have facilitated the investigation of I p in single cardiac myocytes. This review summarizes and discusses the results obtained from I p measurements in isolated cardiac cells. These results offer new exciting insights into the voltage and ionic dependence of the Na+-K+ pump activity, its effect on membrane potential, and its modulation by hormones, transmitters, and drugs. They are fundamental for our current understanding of Na+-K+ pumping in electrically excitable cells.

Hyperthyroid adult rat cardiomyocytes. I. Nucleotide content, beta- and alpha-adrenoreceptors, and cAMP production

1989 ◽  
Vol 257 (5) ◽  
pp. C948-C956 ◽  
Author(s):  
C. M. Hohl ◽  
S. Wetzel ◽  
R. H. Fertel ◽  
D. K. Wimsatt ◽  
G. P. Brierley ◽  
...  
Keyword(s):  
Ventricular Myocytes ◽  
Adenine Nucleotide ◽  
Phosphodiesterase Inhibitor ◽  
Cardiac Cells ◽  
Beta Agonist ◽  
Camp Production ◽  
Adult Rats ◽  
Rat Cardiomyocytes ◽  
Adult Rat ◽  
Half Maximal Effective Concentration

Ventricular myocytes isolated from the hypertrophied hearts of thyrotoxic adult rats have an increase in mean protein content per myocyte (6.3 +/- 0.2 vs. 4.4 +/- 0.2 ng) compared with euthyroid cells. Viability and adenine nucleotide profiles are similar in both populations, but NAD content of the hyperthyroid myocytes is depressed (4.9 +/- 0.2 vs. 5.5 +/- 0.2 nmol/mg for controls) and UTP is higher (1.2 +/- 0.09 vs. 0.9 +/- 0.04 nmol/mg). Binding of (-)-[125I]iodocyanopindolol to intact hyperthyroid myocytes is increased by 42% compared with controls, with no change in the dissociation constant (Kd). This elevation in beta-receptor number is correlated to enhanced beta-agonist-induced adenosine 3',5'-cyclic monophosphate (cAMP) production. The half-maximal effective concentration (EC50) for the euthyroid isoproterenol dose-response curve is 2.14 x 10(-7) M but is decreased to 2.51 x 10(-8) M in hyperthyroid cardiac cells. Basal adenylate cyclase activity is apparently not affected by thyroid hormones, since basal cAMP levels for both groups are identical (5 pmol/mg) and both rise roughly twofold in the presence of a phosphodiesterase inhibitor. Forskolin-induced cAMP production and cAMP-specific phosphodiesterase activity are similar as well. In contrast to beta-adrenergic response, there are no significant differences in alpha 1-antagonist [3H]prazosin binding parameters between hyperthyroid and euthyroid cardiomyocytes.

A new method for preparation of isolated single adult myocytes

1984 ◽  
Vol 247 (6) ◽  
pp. H1018-H1026 ◽  
Author(s):  
G. Bkaily ◽  
N. Sperelakis ◽  
J. Doane
Keyword(s):  
Dispersion Medium ◽  
Cardiac Cells ◽  
New Method ◽  
New Technique ◽  
Resting Potential ◽  
High Yield ◽  
Promising Technique ◽  
Mechanical Method ◽  
Adult Rat ◽  
A New Technique

A new technique for isolation of single cardiac cells from adult rat ventricles is described. The mechanical method is modified from the method of Jacobson (Cell Struct. Funct. 2: 1-9, 1977) by employing an enzyme-free dispersion medium containing Sr2+ or Ba2+ to replace Ca2+. This method produces a high yield of isolated rod-shaped adult mammalian cardiomyocytes that do not contract spontaneously, have a normal resting potential, and are Ca2+ tolerant. This method represents a promising technique for isolation of single, viable, intact, adult myocytes.

scholarly journals Functional localization of cAMP signalling in cardiac myocytes

2006 ◽  
Vol 34 (4) ◽  
pp. 484-488 ◽  
Author(s):  
G. Vandecasteele ◽  
F. Rochais ◽  
A. Abi-Gerges ◽  
R. Fischmeister
Keyword(s):  
Spatial Organization ◽  
Molecular Mechanisms ◽  
Ventricular Myocytes ◽  
Cardiac Cells ◽  
Functional Responses ◽  
Adult Rat ◽  
Cyclic Nucleotide Gated Channels ◽  
Camp Pathway ◽  
Functional Localization ◽  
Heart Physiology

The cAMP pathway is of cardinal importance for heart physiology and pathology. The spatial organization of the various components of the cAMP pathway is thought to allow the segregation of functional responses triggered by the different neuromediators and hormones that use this pathway. PDEs (phosphodiesterases) hydrolyse cAMP (and cGMP) and play a major role in this process by preventing cAMP diffusion to the whole cytosol and inadequate target activation. The development of olfactory cyclic nucleotide-gated channels to directly monitor cAMP beneath the plasma membrane in real time allows us to gain new insights into the molecular mechanisms responsible for cAMP homoeostasis and hormonal specificity in cardiac cells. The present review summarizes the recent results we obtained using this approach in adult rat ventricular myocytes. In particular, the role of PDEs in the maintenance of specific cAMP signals generated by β-adrenergic receptors and other Gs-coupled receptors will be discussed.

Development of a linear transient model for stimulation of isolated cardiac cells

2000 ◽  
Vol 12 (3) ◽  
pp. 217-222 ◽  
Author(s):  
P. Pham ◽  
G. Cauffet ◽  
A. Bardou ◽  
J. Olivares ◽  
E. Novakov
Keyword(s):  
Cardiac Cells ◽  
Transient Model ◽  
Isolated Cardiac Cells ◽  
Stimulation Of

Adenosine stimulation of AMP deaminase activity in adult rat cardiac myocytes

1993 ◽  
Vol 264 (1) ◽  
pp. C48-C53 ◽  
Author(s):  
B. Hu ◽  
R. A. Altschuld ◽  
C. M. Hohl
Keyword(s):  
Ventricular Myocytes ◽  
Cardiac Cells ◽  
Adenosine A1 Receptor ◽  
Nucleoside Transport ◽  
Amp Deaminase ◽  
Adult Rat ◽  
Adenosine A1 ◽  
Adenosine Transport ◽  
A1 Receptor

Using an in situ assay for analyzing AMP deaminase activity in isolated adult rat ventricular myocytes, we have shown that IMP production is stimulated approximately twofold in cardiac cells incubated with 10 microM adenosine. This effect of adenosine was not blocked by the adenosine A1-receptor antagonist 8-cyclophenyl-1,3-dipropylaxanthine (0.01-1 microM) except at a concentration (100 microM) that may inhibit adenosine transport. Similarly, in situ AMP deaminase activity was not enhanced by treatment with the specific adenosine A1-receptor agonists N6-phenylisopropyl adenosine or cyclopentyladenosine, nor was it sensitive to prior treatment of cells with pertussis toxin. The nucleoside transport blockers S-4-nitrobenzyl-6-thioinosine, dipyridamole, and papaverine inhibited adenosine-induced increases in IMP production by 75-85%, suggesting an intracellular site of action. Modulation of enzyme activity via the transmethylation pathway could not be implicated since incubation of cardiac cells under conditions known to elevate intracellular S-adenosyl-L-homocysteine had no demonstrable effect on AMP deaminase. Furthermore, a direct allosteric effect of adenosine on the partially purified rat cardiac enzyme was not observed. The results indicate that intracellular adenosine modulates rat cardiac AMP deaminase by an unknown mechanism.

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