scholarly journals Adrenergic stimulation of substrate utilization by cardiac myocytes isolated from rainbow trout

1991 ◽  
Vol 159 (1) ◽  
pp. 185-202 ◽  
Author(s):  
C. L. Milligan
Keyword(s):  
Rainbow Trout ◽  
Lactate Dehydrogenase ◽  
Cardiac Myocytes ◽  
Trypan Blue ◽  
Glycogen Content ◽  
Substrate Utilization ◽  
Co2 Production ◽  
Adrenergic Agonists ◽  
Adrenergic Stimulation ◽  
Stimulation Of

A method is described for the isolation of calcium-tolerant myocytes from adult rainbow trout. Isolated myocytes remain viable for at least 4 h in suspension as indicated by (1) maintenance of ATP, phosphocreatine (PCr) and glycogen levels; (2) maintenance of the integrity of cell membranes, shown by low rates of leakage of lactate dehydrogenase (LDH) to the medium and exclusion of Trypan Blue; (3) the ability to metabolize substrates; and (4) sensitivity to adrenergic agonists. CO2 production from both glucose and lactate was sensitive to adrenergic stimulation, with the following order of potency: isoproterenol greater than noradrenaline much greater than adrenaline greater than phenylephrine, which indicates the presence of beta 1-adrenoceptors. Myocytes isolated from trout acclimated to 20 degrees C in the summer were more sensitive to beta-adrenergic stimulation than myocytes isolated from trout acclimated to 9 degrees C in either summer or winter. In the absence of exogenous fuel, there was a net reduction in myocyte glycogen content and glycogenolysis was further stimulated by 10(−7) mmol l-1 noradrenaline. However, in the presence of exogenous fuel (either 5 mmol l-1 lactate or 5 mmol l-1 glucose), glycogen was ‘spared’ and noradrenaline-stimulated glycogenolysis was apparently inhibited.

ANTAGONISM BETWEEN INSULIN AND SELECTIVE ADRENERGIC AGONISTS ON THE GLYCOGEN SYNTHETASE AND PHOSPHORYLASE SYSTEMS OF THE ISOLATED RAT DIAPHRAGM

1975 ◽  
Vol 78 (2) ◽  
pp. 392-400
Author(s):  
Arne T. Hostmark ◽  
Ole Grønnerød ◽  
Robert S. Horn
Keyword(s):  
Glycogen Metabolism ◽  
Rat Diaphragm ◽  
Adrenergic Agonists ◽  
Adrenergic Stimulation ◽  
Insulin Effect ◽  
Glycogen Synthetase ◽  
Adrenergic Antagonists ◽  
Fasted Rats ◽  
Isolated Rat ◽  
Stimulation Of

ABSTRACT The antagonism between insulin and selective adrenergic stimulation on the converting systems for glycogen synthetase and phosphorylase has been investigated in the isolated rat diaphragm. Insulin significantly inhibited stimulation by terbutaline and noradrenaline of phosphorylase b to a conversion as well as stimulation of glycogen synthetase I to D conversion by these agents. The inhibition by insulin was stronger on the synthetase system than on the phosphorylase system. The insulin effect was not dependent upon the presence of glucose. In diaphragms from 24 h fasted rats the response of the phosphorylase system to both agonists decreased. Inhibition by insulin of terbutaline stimulated phosphorylase conversion was maintained upon fasting while no effect of insulin against stimulation by noradrenaline could be obtained in diaphragms from fasted rats. The effects of fasting and insulin were not influenced by beta adrenergic antagonists (practolol and butoxamine). The results indicate a difference in sensitivity of the synthetase and phosphorylase systems to insulin and suggest that noradrenaline and terbutaline influence glycogen metabolism by differing mechanisms.

scholarly journals NO donors potentiate the β‐adrenergic stimulation of I Ca,L and the muscarinic activation of I K,ACh in rat cardiac myocytes

2002 ◽  
Vol 540 (2) ◽  
pp. 411-424 ◽  
Author(s):  
Najah Abi‐Gerges ◽  
Gabor Szabo ◽  
Angela S. Otero ◽  
Rodolphe Fischmeister ◽  
Pierre‐François Méry
Keyword(s):  
Cardiac Myocytes ◽  
Adrenergic Stimulation ◽  
No Donors ◽  
Rat Cardiac Myocytes ◽  
Stimulation Of

Adrenergic stimulation of glycolysis without change in glycolytic enzyme binding in rainbow trout (Oncorhynchus mykiss) erythrocytes

1994 ◽  
Vol 72 (5) ◽  
pp. 950-953 ◽  
Author(s):  
Dawn H. Sephton ◽  
William R. Driedzic
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Whole Blood ◽  
Glycolytic Enzyme ◽  
Adrenergic Stimulation ◽  
Enzyme Binding ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Cell Membrane Binding ◽  
Stimulation Of

Whole blood from rainbow trout (Oncorhynchus mykiss) was incubated in vitro with pharmacological levels of isoproterenol. The adrenergic stimulation of glycolysis in erythrocytes (RBCs) was assessed by monitoring the rate of 14C incorporation from [6-14C]-glucose into the acid-soluble RBC fraction. During a 3-h in vitro incubation, incorporation of label into the acid-soluble RBC fraction of isoproterenol-treated whole blood (0.25 ± 0.04 μmol glucose∙mL−1 RBC∙h−1) was higher than into untreated blood (0.08 ± 0.01 μmol glucose∙mL−1 RBC∙h−1). The percentage of cell membrane binding for phosphofructokinase, aldolase, and glyceraldehyde-3-phosphate dehydrogenase ranged from 17 to 35% and was not altered by adrenergic stimulation. Adrenergic stimulation activates glycolysis in rainbow trout RBCs but not through the modulation of enzyme binding.

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