Alterations in cation homeostasis in cultured chick ventricular cells during and after recovery from adenosine triphosphate depletion.

Ishida, Hideyuki; Kohmoto, Osami; Bridge, John H.B.; Barry, William H.

doi:10.1172/jci113432

Cited by 27 publications

(7 citation statements)

References 40 publications

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“…Constant current pulses (3-8 ms duration) were delivered via a glass capillary tube (70Mtm tip diameter) filled with NT and positioned -0.1 mm from the cell. Chick myocytes were paced at 3 Hz, and rabbit myocytes at 0. during metabolic inhibition in these experiments by means ofa luciferase assay (ATP Bioluminescence CLS; Boehringer Mannheim Corp., Indianapolis, IN) with modification of a previously described method (30). Cover slips ofspontaneously contracting cultured chick myocytes were incubated in NT containing 20 mM 2DG or 1 mM CN for 6 min without pacing.…”

Section: Methodsmentioning

confidence: 99%

Contributions of [Ca2+]i, [Pi]i, and pHi to altered diastolic myocyte tone during partial metabolic inhibition.

Ikenouchi¹,

Kohmoto²,

McMillan³

et al. 1991

J. Clin. Invest.

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Ischemia may cause increased or decreased distensibility of the left ventricle, but the cellular mechanisms involved have not been clarified. We examined the possible contributions of changes in intracellular inorganic phosphate, pH, and Ca2" concentrations to altered diastolic function in cultured myocytes subjected to partial metabolic inhibition. Paced cultured embryonic chick and adult rabbit ventricular myocytes superfused with 20 mM 2-deoxyglucose (2DG) exhibited an increase in end-diastolic intracellular free calcium concentration ([Ca2`J,) and an upward shift in end-diastolic cell position.These results indicate that glycolytic blockade increases diastolic and systolic calcium in paced ventricular myocytes, and that this elevated diastolic calcium influences the extent of diastolic relaxation. In contrast, paced ventricular myocytes superfused with 1 mM cyanide (CN) exhibited a similar increase in end-diastolic [Ca2"ji but a decrease in end-diastolic cell position and amplitude of motion. Although changes in ATP contents were similar in both groups (2DG, -29.9%; CN, -40.1%), alterations of intracellular pH and inorganic phosphate concentrations were different. In 2DG-treated cells, pHi did not decrease significantly (7.18±0.04 to 7.12±0.11, n = 14) but in the CN group it decreased markedly within 6 min (7.18±0.04 to 6.76±0.11, n = 11, P < 0.01). Intracellular inorganic phosphate decreased slightly in the 2DG group (-14.8%, NS) but increased in cells exposed to CN (45.7%, P < 0.02). We conclude that while a prominent increase in diastolic [Ca2+J occurs in rapidly paced ventricular myocytes exposed to either inhibitors of glycolysis or oxidative phosphorylation, the effects of this increase in [Ca2"1 on diastolic distensibility may be influenced by intracellular accumulation of metabolites that decrease the sensitivity of myofilament to [Ca2"J. (J. Clin. Invest.

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Section: Methodsmentioning

confidence: 99%

Contributions of [Ca2+]i, [Pi]i, and pHi to altered diastolic myocyte tone during partial metabolic inhibition.

Ikenouchi¹,

Kohmoto²,

McMillan³

et al. 1991

J. Clin. Invest.

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“…Appropriate geometric corrections and activity standards were combined with generator equilibrium equations in the case of 9'Tc (see Reference 37) To determine the effect of metabolic inhibition on net accumulation of 99mTc-SESTAMIBI and 201H1, preparations were immersed at time zero in buffer containing the metabolic inhibitors and either 9'9Tc-SESTAMIBI or '01T1, removed after long times of incubation, and processed as described above. To determine the effect of ATP depletion on net retention of the agents, preparations were loaded to plateau in control buffer containing 9"'Tc-SESTAMIBI (60 …”

Section: Solutionsmentioning

confidence: 99%

Divergent kinetics of 201Tl and 99mTc-SESTAMIBI in cultured chick ventricular myocytes during ATP depletion.

1992

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BACKGROUND Thallous chloride (201Tl) and hexakis(2-methoxyisobutyl isonitrile) technetium (I) (99mTc-SESTAMIBI) are myocardial perfusion imaging agents with biological properties that also reflect tissue viability. Initial myocellular uptake rates of 201Tl reflect activity of Na,K-ATPase, whereas those of 99mTc-SESTAMIBI reflect mean plasma membrane potential. METHODS AND RESULTS To better understand the mechanistic responses of these tracers to myocellular injury, cultured chick embryo cardiac myocytes were metabolically inhibited in iodoacetate (1 mM) and rotenone (10 microM) for up to 2 hours, and initial uptake rates of each agent were determined at successive intervals along with correlative cellular contents of ATP, sodium, and potassium and lactate dehydrogenase release. ATP content fell from 30.5 +/- 1.4 to 2.7 +/- 0.9 nmol.(mg protein)-1 within 2 minutes, whereas sodium and potassium contents ran down their thermodynamic gradients more slowly (t 1/2 approximately 60 minutes). Modestly severe cell injury was produced at 2 hours as estimated by lactate dehydrogenase release (18% of total). Initial uptake rates of 201Tl declined from 6.9 +/- 0.8 to 4.0 +/- 0.4 fmol.(mg protein)-1.(nMo)-1.(min)-1 by 20 minutes and remained depressed and ouabain (100 microM)-insensitive at 30 +/- 13% of control. Conversely, initial uptake rates of 99mTc-SESTAMIBI increased from 10.6 +/- 0.8 to 15.0 +/- 0.6 fmol.(mg protein)-1.(nMo)-1.(min)-1 within 10 minutes, remained elevated for 40-60 minutes, and later declined to low values. Injury-induced enhancement of initial uptake rates of 99mTc-SESTAMIBI were insensitive to ouabain (100 microM), carbonyl cyanide-m-chlorophenyl hydrazone (5 microM), and valinomycin (1 microgram/ml) but were significantly inhibited by 130 mM Ko buffer, Ba2+ (1 mM), glybenclamide (100 microM), and quinacrine (10 microM). CONCLUSIONS Uptake rates of 201Tl monotonically decline, correlating with Na-K pump inhibition from ATP depletion. Conversely, uptake rates of 99mTc-SESTAMIBI at first increase above control for 40-60 minutes, indicating a mean plasma membrane hyperpolarization possibly resulting from opening of ATP-sensitive and arachidonic acid-activated potassium channels, before declining to low values with more severe cell injury. Correlative non-flow-dependent relations between 201Tl and 99mTc-SESTAMIBI contain information regarding the degree of myocellular injury.

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“…78 ]j measurements. To minimize these problems, we limited the duration of exposure to hypoxia and ischemia to short periods during which significant shifts in ATP concentrations would not be expected to occur.…”

Section: Sooraacmentioning

confidence: 99%

Direct measurement of changes in intracellular calcium transients during hypoxia, ischemia, and reperfusion of the intact mammalian heart.

Kihara

Grossman

1989

Circulation Research

274

123

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In studies of ischemia and reperfusion, a major experimental problem has been the inability to measure intracellular ionized calcium ([Ca 2 *])) in the intact heart. We have developed a new approach in which the bioluminescent calcium indicator aequorin is used to measure [Ca 2+ ], in the isolated, coronary-perfused ferret heart. Aequorin is loaded into subepicardial myocytes of the left ventricle, and the signals are recorded simultaneously along with isovolumic left ventricular (LV) pressure at a constant pacing rate. This system shows 1) no attenuation or change of time course of LV pressure development or coronary perfusion pressure after aequorin loading; 2) consistent responses to physiological interventions and drugs; 3) individual aequorin and pressure signals that do not require signal averaging for analysis; and 4) [ ]j regulation during ischemia? and 2) how does the rise in [Ca 2+ ]j relate to the mechanical dysfunction that occurs during periods of acute ischemia or after reperfusion?We have developed a new system in which [Ca 2+ ]i transients are obtained reproducibly with the bioluminescent protein aequorin in isolated, coronaryperfused ferret hearts.9 ' 10 This system permits recording of changes in [Ca 21 "], and the corresponding ventricular mechanical parameters on a beatto-beat basis. By means of this system, we delineate the effects of ischemia and hypoxia on intracellular Ca 2+ handling and the responses of the contractile elements to Ca 2+ , which can be correlated with acute changes in ventricular systolic and diastolic function. Our results provide evidence that different by guest on

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Alterations in cation homeostasis in cultured chick ventricular cells during and after recovery from adenosine triphosphate depletion.

Cited by 27 publications

References 40 publications

Contributions of [Ca2+]i, [Pi]i, and pHi to altered diastolic myocyte tone during partial metabolic inhibition.

Contributions of [Ca2+]i, [Pi]i, and pHi to altered diastolic myocyte tone during partial metabolic inhibition.

Divergent kinetics of 201Tl and 99mTc-SESTAMIBI in cultured chick ventricular myocytes during ATP depletion.

Direct measurement of changes in intracellular calcium transients during hypoxia, ischemia, and reperfusion of the intact mammalian heart.

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