Review: Isolated cardiac myocytes: II Functional aspects of mature cells

Dow, Jocelyn W.; Harding, Nigel G. L.; Powell, T.

doi:10.1093/cvr/15.10.549

Cited by 63 publications

(17 citation statements)

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“…Octanoate and ,Bhydroxybutyrate were observed to inhibit, and insulin and isoproterenol to stimulate glucose oxidation (table 2). The concentration of ATP in these cells was measured and was found to be similar (25 nmol/mg protein) to that reported for intact heart muscle [16,17,19].…”

Section: Resultssupporting

confidence: 75%

“…1). These data are expressed in terms of oxygen equivalents so that the oxidation of the different substrates can be compared with each other and with data obtained by others in studies utilizing the in situ and isolated perfused heart and freshly isolated myocytes [ 18-221. Similar to data reported by others [19,21,22] we (table 1) also find that freshly isolated heart myocytes prefer carbohydrate over fatty acid as a substrate. To determine when during the culture period this change in preferring glucose (freshly isolated cells) to preferring octanoate (cultured cells) occurs, we measured the oxidation of these substrates at various times after initially placing the cells in culture.…”

Section: Atp Analysissupporting

confidence: 90%

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Culture of the terminally differentiated ventricular cardiac muscle cell

1984

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Oxidation of several exogenous substrates by cultured adult rat ventricular cardiac muscle cells has been assessed. Unlike freshly isolated cardiac muscle cells which oxidize glucose preferentially, the cultured cells more closely resemble metabolically the in situ heart and the isolated perfused heart, in that their preference for exogenous substrates is in the order of fatty acid > glucose. This switch in metabolic preference from glucose to fatty acid is complete within 12 h after placing freshly isolated cells in culture. Glucose oxidation is stimulated by insulin and isoproterenol and inhibited by fl-hydroxybutyrate and octanoate. The adenylate cyclase system has also been examined in these cultured cells. Isoproterenol, norepinephrine and epinephrine stimulate the accumulation of cyclic adenosine 3' : S-monophosphate (cyclic AMP) in a concentration-dependent manner. The order of potency is isoproterenol > norepinephrine g epinephrine. This stimulation is potentiated by 1-isobutyl-3-methylxanthine and inhibited by 1-propranolol. Substrate oxidation Cardiac muscle Adult rat Cell culture MetabolismAdenylate cyclase

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Section: Resultssupporting

confidence: 75%

Section: Atp Analysissupporting

confidence: 90%

Culture of the terminally differentiated ventricular cardiac muscle cell

1984

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“…(CircRes 56:195-204, 1985) FRESHLY dissociated cells are becoming preparations of choice for many physiological and biochemical studies. Interpretation of data from these studies depends on the extent to which the morphological and physiological properties of the dissociated cells correspond to those of the intact tissue, an issue addressed in heart by recent reviews by Dow et al (1981aDow et al ( , 1981b. Of particular interest to us is the fact that many cells are connected by intercellular junctions in situ: therefore, the dissociation process must alter the specialized regions of intercellular contact.…”

Section: From the Departments Of Neuroscience And Physiology Albert mentioning

confidence: 99%

Fate of intercellular junctions in isolated adult rat cardiac cells.

Mazet¹,

Wittenberg²,

Spray³

1985

Circulation Research

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SUMMARY. Freeze fracture and thin section techniques have revealed morphological changes in gap junctions and intercalated discs of adult rat myocytes following enzymatic dissociation. Cell separation leaves behind small vesicular remnants of formerly adjacent cells connected to the intact cell by gap junctions; in contrast, desmosomes cleave at the region of intercellular contact. Apparently, the next step in gap junction breakdown is intemalization of the remnants. In thin section, lanthanum penetration reveals that the cleft of some apparently internalized gap junctions is in contact with the sarcolemma, while that of others is not. In freeze fracture replicas, cytoplasmic gap junctions frequently possess hexagonally packed domains of E-face pits separated by smooth regions that may correspond to separations of membranes of internalized junctions found in thin section. Study of material maintained overnight at 37°C showed no surface junctional remnants; topologies of cytoplasmic gap junctions were generally complex, and concentric membrane vesicles were common. These observations suggest that enzymatic dissociation initiates a progressive, defined sequence of junctional intemalization that begins with attached cell remnants and may have as the last determinable step the separation into single membranes inside the intact cell. (CircRes 56:195-204, 1985)

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“…Single isolated myocytes were prepared from the ventricles of adult guinea pigs and bovine hearts by enzymatic Downloaded from http://ahajournals.org by on March 31, 2019 288 dissociation (Glick et al, 1974;Dow et al, 1981). The ventricular myocytes of the guinea pig hearts were enzymatically isolated by retrograde perfusion of the aorta ("perfusion method"), whereas, the myocytes of bovine hearts were isolated by incubating ventricular tissue chunks in enzyme medium ("chunk method") (Isenberg and Klockner, 1982a).…”

Section: Cell Preparationmentioning

confidence: 99%

“…Thus, in the intact heart, it seems that adenosine can act both prejunctionally, at the level of adrenergic nerve terminals, and postjunctionally, at the level of the cardiac cells. The postjunctional effects of adenosine can be better investigated in the isolated cells since they are free of hormonal influences and devoid of nerve terminals (Fry et al, 1979;Dow et al, 1981).…”

mentioning

confidence: 99%

Actions of adenosine and isoproterenol on isolated mammalian ventricular myocytes.

Belardinelli¹,

Isenberg²

1983

Circulation Research

181

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SUMMARY. We investigated the effects of adenosine and isoproterenol on enzymatically dispersed ventricular myocytes from bovine and guinea pig hearts. Inrracellular stimulation of relaxed myocytes with regular srriation patterns and normal resting potential resulted in action potentials with full plateaus accompanied by contractions. Adenosine in concentrations up to 0.2 HIM had no significant effect on any of the action potential parameters or on the basal contractility. In contrast, in the same cells, adenosine effectively antagonized the stimulatory effect of isoproterenol. Isoproterenol (1-10 nM) prolonged the action potentials by 34-41%, displaced the plateau to more positive potentials, and caused a 3-fold increase in the extent of myocyte sarcomere shortening. In the presence of adenosine (5-50 HM), isoproterenol increased the action potential duration by only 8-9%, the shift of the plateau was nearly abolished, and the increase in the extent of myocyte sarcomere shortening was less than 10%. In some of the myocytes, isoproterenol (1-10 nM) induced depolarizing afterpotentials accompanied by aftercontractions. The afterdepolarizations occasionally reached threshold resulting in triggered sustained rhythmic activity. Adenosine (20-50 HM) not only reduced the amplitude of the afterdepolarizarions and aftercontractions, but also abolished the sustained rhythmic activity. We conclude, first, that isolated ventricular myocytes respond to isoproterenol and adenosine; second, that adenosine has no direct effect, but effectively antagonizes the stimulatory actions of isoproterenol; third, that findings are consistent with the ones reported for multicellular ventricular preparations; fourth, that adenosine concentrations required to attenuate the actions of isoproterenol are in the range of adenosine concentrations released by cardiac cells when oxygen availability is limited and/or demand is increased; and fifth, that endogenously released adenosine may modulate the electrophysiological and contractile effects of catecholamines. (Circ Res 53: 287-297, 1983) RECENTLY, adenosine has been recognized to antagonize specifically the inotropic, and some of the electrophysiological and metabolic, effects of catecholamines in ventricular myocardium (Schrader et al., 1977;Dobson, 1978;Baumann et al., 1981, Belardinelli et al., 1982.The observation that adenosine antagonizes the inotropic effect of tyTamine, but not the tyramineinduced release of norepinephrine, has been assumed to indicate that adenosine acts postsynaptically (Schrader et al., 1979). However, adenosine has also been shown to inhibit the stimulationinduced release of norepinephrine from sympathetic nerve terminals in the heart (Hedquist and Fredholm, 1976;Wakade and Wakade, 1978). Consistent with this latter finding, in the dog, adenosine has been shown to reduce the increase in heart rate induced by electric stimulation of the right stellate ganglion (Horn and Lokhandwala, 1981). These observations suggest that the antagonism between adenosine and sympa...

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Review: Isolated cardiac myocytes: II Functional aspects of mature cells

Cited by 63 publications

References 0 publications

Culture of the terminally differentiated ventricular cardiac muscle cell

Culture of the terminally differentiated ventricular cardiac muscle cell

Fate of intercellular junctions in isolated adult rat cardiac cells.

Actions of adenosine and isoproterenol on isolated mammalian ventricular myocytes.

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