The effect of calcium on cardiac phosphorylase activation, contractile force and cyclic AMP in euthyroid and hyperthyroid rat hearts

1976 ◽  
Vol 54 (4) ◽  
pp. 590-595 ◽  
Author(s):  
Elizabeth J. Hartley ◽  
John H. McNeill
Keyword(s):  
Enzyme Activity ◽  
Thyroid Hormone ◽  
Cyclic Amp ◽  
Positive Inotropic Effect ◽  
Contractile Force ◽  
Inotropic Effect ◽  
Chronotropic Effect ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Isolated Perfused Rat Hearts

Calcium chloride injected into isolated perfused rat hearts produced a positive inotropic effect and increased the levels of phosphorylase a (EC 2.4.1.1). The increase in enzyme activity lagged behind the inotropic effect. Pretreatment of animals with thyroid hormone enhanced the ability of noradrenaline to activate phosphorylase but did not affect the inotropic or phosphorylase activating effect of calcium. Thyroid hormone pretreatment did enhance the chronotropic effect of calcium. Calcium did not affect the cardiac levels of cyclic AMP. It is concluded that calcium can activate phosphorylase by a mechanism other than cyclic AMP and that the enhancement of adrenergic amine-induced phosphorylase activation by thyroid hormone is not a calcium mediated event.

Cyclic AMP and the positive inotropic effect of norepinephrine and phenylephrine

1977 ◽  
Vol 55 (2) ◽  
pp. 279-287 ◽  
Author(s):  
T. T. Martinez ◽  
J. H. McNeill
Keyword(s):  
Cyclic Amp ◽  
Cell Membrane ◽  
Time Course ◽  
Positive Inotropic Effect ◽  
Contractile Response ◽  
Contractile Force ◽  
Time Response ◽  
Inotropic Effect ◽  
Chronotropic Response ◽  
Right Atria

Time-response studies of the effects of norepinephrine and phenylephrine revealed that both agonists caused an increase in cyclic AMP levels before increases in contractile force in either the electrically stimulated left atria or spontaneously beating right atria of the rat. Norepinephrine caused a nearly sixfold increase in cyclic AMP, whereas phenylephrine produced only a 50% increase in the nucleotide. Pretreatment with reserpine did not affect the norepinephrine cyclic AMP response; however, the phenylephrine cyclic AMP response was abolished. Reserpine pretreatment did not significantly affect the contractile responses of either amine. In the presence of propranolol, norepinephrine was found to have the ability to produce an increase in contractile force in which cyclic AMP was apparently not involved. The time course of the contractile response induced by adrenergic amines was found to be remarkably influenced by the chronotropic response in spontaneously beating preparations while the cyclic AMP response was not greatly affected. This difference in the contractile response may be due to the ability of the chronotropic response to influence the flux of calcium through the cell membrane.

scholarly journals Tissue Distribution and Cardiac Metabolism of 3-Iodothyronamine

Endocrinology ◽  
2010 ◽  
Vol 151 (10) ◽  
pp. 5063-5073 ◽  
Author(s):  
Alessandro Saba ◽  
Grazia Chiellini ◽  
Sabina Frascarelli ◽  
Maja Marchini ◽  
Sandra Ghelardoni ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Amine Oxidase ◽  
Cardiac Metabolism ◽  
Rat Serum ◽  
Rat Hearts ◽  
H9c2 Cardiomyocytes ◽  
Perfused Rat Hearts ◽  
First Time ◽  
G Protein Coupled ◽  
Isolated Perfused Rat Hearts

3-Iodothyronamine (T1AM) is a novel relative of thyroid hormone, able to interact with specific G protein-coupled receptors, known as trace amine-associated receptors. Significant functional effects are produced by exogenous T1AM, including a negative inotropic and chronotropic effect in cardiac preparations. This work was aimed at estimating endogenous T1AM concentration in different tissues and determining its cardiac metabolism. A novel HPLC tandem mass spectrometry assay was developed, allowing detection of T1AM, thyronamine, 3-iodothyroacetic acid, and thyroacetic acid. T1AM was detected in rat serum, at the concentration of 0.3 ± 0.03 pmol/ml, and in all tested organs (heart, liver, kidney, skeletal muscle, stomach, lung, and brain), at concentrations significantly higher than the serum concentration, ranging from 5.6 ± 1.5 pmol/g in lung to 92.9 ± 28.5 pmol/g in liver. T1AM was also identified for the first time in human blood. In H9c2 cardiomyocytes and isolated perfused rat hearts, significant Na+-dependent uptake of exogenous T1AM was observed, and at the steady state total cellular or tissue T1AM concentration exceeded extracellular concentration by more than 20-fold. In both preparations T1AM underwent oxidative deamination to 3-iodothyroacetic acid. T1AM deamination was inhibited by iproniazid but not pargyline or semicarbazide, suggesting the involvement of both monoamine oxidase and semicarbazide-sensitive amine oxidase. Thyronamine and thyroacetic acid were not detected in heart. Finally, evidence of T1AM production was observed in cardiomyocytes exposed to exogenous thyroid hormone, although the activity of this pathway was very low.

scholarly journals The release of 3′:5′-cyclic monophosphate from the isolated perfused rat heart

1975 ◽  
Vol 152 (2) ◽  
pp. 429-432 ◽  
Author(s):  
John A. O'Brien ◽  
Richard C. Strange
Keyword(s):  
Cyclic Amp ◽  
Rat Heart ◽  
Perfused Rat Heart ◽  
Cyclic Monophosphate ◽  
Isolated Perfused Rat Heart ◽  
Rat Hearts ◽  
Basal Release ◽  
Perfused Rat Hearts ◽  
Isolated Perfused Rat Hearts

Although basal release of cyclic AMP from isolated perfused rat hearts was not measurable, isoprenaline induced substantial release of the nucleotide, suggesting that in vivo the myocardium can contribute to plasma cyclic AMP. Anoxia also increased the amount of cyclic AMP released, but insulin and nicotinate alone or in combination had no effect.

Cardiac staircase and NMR-determined intracellular sodium in beating rat hearts

1995 ◽  
Vol 269 (1) ◽  
pp. H332-H340
Author(s):  
C. S. Lotan ◽  
S. K. Miller ◽  
T. Simor ◽  
G. A. Elgavish
Keyword(s):  
Positive Inotropic Effect ◽  
Diastolic Pressure ◽  
Systolic Pressure ◽  
Progressive Increase ◽  
Inotropic Effect ◽  
Enhanced Sensitivity ◽  
Group I ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Group Ii

Isolated, perfused rat hearts (30 degrees C, n = 13) were paced from 218 +/- 4 beats/min to 433 +/- 4 beats/min while systolic and diastolic pressure were recorded and intracellular Na+ concentration ([Na+]i) was monitored by 23Na nuclear magnetic resonance (NMR) spectroscopy. [Na+]i increased progressively with increasing stimulation frequency. In seven hearts (group I) an initial, progressive increase in systolic pressure was observed followed by a decrease in pressure with further increase in frequency. From the onset, a progressive decrease in systolic pressure was observed in group II (n = 6) in response to increased frequency. In group I an [Na+]i increase of up to 134 +/- 7% of control (P < 0.001) was observed, whereas in group II the gain in [Na+]i with increasing pacing rate was attenuated, reaching a maximum of 120 +/- 3% of control (P < 0.02). The differential pressure response between group I and group II hearts may reflect an enhanced sensitivity of rat hearts to the shortening of the restitution period of the sarcoplasmic reticulum, outweighing the positive inotropic effect induced by an increased [Na+]i. Only in rat hearts whose [Na+]i-induced increase in pressure outweights the restitution deficit would a complete positive inotropic effect be anticipated.

Developmental increase in the inotropic and cyclic AMP response to isoproterenol in embryonic and newly hatched chicks

1989 ◽  
Vol 67 (9) ◽  
pp. 1109-1111 ◽  
Author(s):  
Ken Nakazawa ◽  
Yutaka Kusuya ◽  
Koki Shigenobu
Keyword(s):  
Cyclic Amp ◽  
Positive Inotropic Effect ◽  
Developmental Stages ◽  
Sympathetic Innervation ◽  
Contractile Force ◽  
Inotropic Effect ◽  
Chick Embryos

The cyclic adenosine 3′,5′-monophosphate (cyclic AMP) levels of ventricles isolated from 15- to 20-day-old chick embryos and 0- to 3-day-old hatched chicks were compared to clarify the mechanism underlying the change in sensitivity to isoproterenol during perinatal developmental stages when the functional sympathetic innervation has been completely achieved. Isoproterenol produced a positive inotropic effect on ventricles isolated from both embryonic and hatched chicks, but the ventricles from the hatched chicks were more sensitive. At both developmental stages sotalol was an equipotent antagonist of isoproterenol. 3-Isobutyl-1-methylxanthine (IBMX) produced an increment in the contractile force of the ventricles at both stages, but the ventricles from the hatched chicks responded to lower doses of IBMX. The reactivity to isoproterenol in increasing cyclic AMP level was significantly higher in the hatched ventricles than in the embryonic ventricles. The results suggest that the different sensitivities to isoproterenol between embryonic and newly hatched chick ventricles may be due to some changes in the process for cyclic AMP production.Key words: chick ventricle, development, β-adrenergic sensitivity, cyclic AMP.

scholarly journals Enhanced G i Signaling Selectively Negates β 2 -Adrenergic Receptor (AR)– but Not β 1 -AR–Mediated Positive Inotropic Effect in Myocytes From Failing Rat Hearts

Circulation ◽  
2003 ◽  
Vol 108 (13) ◽  
pp. 1633-1639 ◽  
Author(s):  
Rui-Ping Xiao ◽  
Sheng-Jun Zhang ◽  
Khalid Chakir ◽  
Pavel Avdonin ◽  
Weizhong Zhu ◽  
...  
Keyword(s):  
Adrenergic Receptor ◽  
Positive Inotropic Effect ◽  
Inotropic Effect ◽  
Rat Hearts
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