Isolated Heart Cells Research Articles

Eosinophilia and hypereosinophilic syndromes

Man, unlike most other animals, has a marked capacity to develop high blood eosinophil counts. This can occur in many tropical diseases especially parasitic infections and hypersensitivity reactions to a variety of antigens. In temperate climates a marked eosinophilia is more commonly due to drug reactions and tumours, but as many as a half of patients with a persistent eosinophilia may have no defined aetiology detectable. Among 80 patients with an eosinophilia seen in London, 47% were of known aetiology: 20% were due to parasitic diseases in immigrants and 21% were drug-induced. In 52% of the patients no cause could be found: 31% had ‘the hypereosinophilic syndrome’, 10% had the polyarteritis group of diseases and 7% pulmonary eosinophilia. Some of the tissue lesions seen in these syndromes, especially the cardiac and neurological damage, may be caused by products released from degranulating eosinophils. Stimulation of secretion occurs with complexes and C3b. Direct killing of isolated heart cells has been found with eosinophil secretion products and a number of cells and parasites are known to be killed by eosinophil basic protein. It is concluded that the eosinophils are prominent in many clinical settings beside parasitic diseases. The secretion of the eosinophil granule contents can have a range of effects on tissues including severe tissue injury.

An improved procedure for the high-yield preparation of intact beating heart cells from the adult rat biochemical and morphologic study

An improved procecedure for the preparation of intact isolated heart cells in high yield from the adult rat is described. The heart was perfused first with Ca 2+-free bicarbonate-buffered balanced salt solution, then with the same solution containing 0.5% collagenase and 0.2% hyaluronidase, followed by the same solution containing 0.5 m m ethylenediamine tetra acetate, 30 m m taurine and 10% ( v v ) dimethylsulphoxide. The inclusion of dimethylsulphoxide protected the cells against degeneration during isolation and also permitted physiological levels of Ca 2+ to stimulate beating fully without inducing cell damage. No adverse effects of dimethylsulphoxide on the fine structure of isolated heart cells were observed. Intactness of the cells was assessed by light and electron microscopy as well as biochemical measurements. The fine structure of intact cells was indistinguishable from that of rat myocardial cells in situ. A close correlation between morphological appearance and function was noted. The rate of respiration and the content of lactate dehydrogenase and adenine nucleotides in isolated cell suspensions were found to be directly related to the proportion of morphologically intact cells. Isolated heart cells prepared by this procedure were responsive to the hormones epinephrine and insulin. In addition, approximately 80% of the cells were stimulated to beat by the addition of physiological levels of Ca 2+ and continued to do so for periods up to 30 min without appreciable disturbance of normal structure. The cells remained intact for up to 1 h if stored at 0 to 4°C. Storage of the cell suspension for periods over 1 h resulted in a cell population which contained a lower proportion of intact cells and which was less tolerant to Ca 2+. The present isolation procedure for adult rat heart cells is considered to be a substantial improvement on existing methods since it allows the relatively simple preparation of intact cells that do not immediately degenerate when exposed to physiological levels of Ca 2+ and are thus more suitable for biochemical and pharmacological studies.

Uptake and release of adenosine in the presence of lidoflazine and carbochromen in isolated heart cells: S.J.Mustafa and C.F.Smith, Department of Pharmacology, University of South Alabama College of Medicine, Mobile, Albama, USA

Uptake and release of adenosine in the presence of lidoflazine and carbochromen in isolated heart cells: S.J.Mustafa and C.F.Smith, Department of Pharmacology, University of South Alabama College of Medicine, Mobile, Albama, USA

Open chain crown-type polyethers and pyridinophane cryptands act as ionophores upon frog motor nerve and isolated rat heart cells

Frog motor nerves and isolated heart cells from neonatal rats were incubated with solutions of open chain crown-type polyether or pyridinophane cryptand. The following alterations in membrane excitability and energy consumption were found: 1. 1. The non-cyclic ligand stabilizes the resting potential of the frog nerve and reduces the pulsation rate of heart muscle cells. It is reversibly bound at the cell surface and does not affect the energy metabolism of the heart cells. 2. 2. The cryptand 1,12-dioxo-2,11-diaza-5,8,21,24-tetraoxa[12-8 2,11](2,6)-pyridinophane) ([2.2.1. Py]-diamide) is irreversibly bound by the tissues. It facilitates the depolarization of the nerve and shows a positively chronotropic effect upon the heart muscle cells. Single treatment of the cell cultures with 10 μg [2.2.1 Py]-diamide per ml medium increased the activities of lactate dehydrogenase and of creatine kinase. When the cell cultures were treated three times at 24 h intervals with 10 μg complexone/ml, the creatine kinase activity of the heart muscle cells decreased by about 40%. The physiological properties of the ligands are correlated with the stability of their alkali metal ion complexes and with the rate constants of complex formation. It is concluded that [2.2.1 Py]-diamide can act as a passive carrier for Na + and K +.

Glucose and octanoate utilization by isolated adult rat heart cells

Rat heart muscle cells continue to beat in the isolated state apparently independent of any innervation. The oxidation of 14C-glucose to 14CO 2 was linear for at least 60 minutes of incubation. The rate of glucose oxidation rose rapidly up to a medium glucose concentration of 2.5 mM and then plateaued. Lactate production reached a maximum at 5 mM glucose. Glucose uptake was linearly related to the concentration up to 40 mM. The addition of octanoate reduced, but did not eliminate, glucose oxidation. Octanoate utilization increased with increasing concentration and reached a maximum at 2 mM. The oxidation of octanoate was linearly related to the time of incubation for at least 90 minutes. The presence of glucose, at a concentration of 1.25 mM or higher, increase the oxidation of octanoate by the heart cells. The metabolic parameters measured with the isolated heart cells gave values comparable to those obtained with the perfused rat heart. Decreasing or increasing the concentration of sodium, potassium or magnesium did not effect the oxidation of either glucose or octanoate with the exception that when sodium was increased above 200 mM, a significant increase in glucose oxidation was observed. In contrast, the addition of calcium to a calcium free medium increased glucose oxidation, reaching a maximum at 0.2 mM calcium. The oxidation of octanoate reached a maximum at 0.2 mM and then decreased significantly with increasing calcium concentration. The metabolic activity appears to be independent of the concentration of sodium, potassium or magnesium. In contrast, the isolated heart cell is very sensitive to a change in calcium concentration.

Amino acid uptake in isolated chick embryo heart cells.

1. The preparation of cell suspensions by treatment of chick embryo hearts with collagenase at various stages of development is described. 2. Measurements of oxygen consumption, incorporation of labelled leucine into protein and accumulation of labelled alpha-aminoisobutyric acid against a concentration gradient indicated a long-lasting viability of the isolated heart cells in vitro; a satisfactory preservation of subcellular structures, including plasma membrane, was assessed by electron-microscopic examination. 3. The rate of alpha-aminoisobutyric acid accumulation by cardiac cells isolated from hearts at different stages of embryological development decreased with aging; insulin stimulated the intracellular accumulation of this amino acid analogue. 4. Insulin increased the uptake by isolated heart cells of several (14)C-labelled naturally occurring amino acids; however, the fraction of amino acid taken up by the cells that was recovered free intracellularly, and therefore the concentration ratio (between intracellular water and medium), was enhanced by the hormone only with glycine, proline, serine, threonine, histidine and methionine. When isolated heart cells were incubated in the presence of a mixture of labelled amino acids, the addition of insulin increased the disappearance of radioactivity from the medium. 5. The general pattern of amino acid transport (in the absence and in the presence of insulin) in isolated cardiac cells was similar to that found in intact hearts, suggesting that the biological preparation described in this paper might be useful for studies of cell permeability and insulin action.

Sustained oscillations of ionic constituents of mitochondria

Optimum conditions for the oscillations of H + and K + concentrations of maximum amplitude and minimum damping factor in pigeon heart mitochondria have been evaluated. Under appropriate conditions, the damping factor falls to 1.5 or even 0.9. Thus, the oscillatory mechanism is essentially of a continuous nature. While oscillations are generally observed in the pH range 6.5–6.0 and at K + concentrations 5–9 m m, optimum conditions for oscillations are most concisely defined in terms of the K + H + ratio between 0.9 and 1.5 × 10 4, with a well-defined optimum, in most cases, at 1.2 × 10 4. Valinomycin concentrations between 90 and 100 ng per milliliter and phosphate concentrations of 2 m m give optimal results. The oscillations have a high temperature coefficient. The time relationships of the parameters H +, K + have been examined in detail, and the phase shift of K + is 180 ° with respect to H +. While a clear-cut control of the phase relationships of the oscillations is not yet obtainable with either K + or H +, additions of the latter at the H + minimum cause a delay in the K + response, suggestive of an involvement of H + concentration in the oscillatory process, but neither K + nor H + are identified as controlling intermediates in the oscillation mechanism. The relationship of the oscillations in the isolated mitochondria has been compared with those observed in heart tissue or isolated heart cells, and, while the periods differ considerably, the fact that both are ATP-activated is of interest. It is now apparent that both the mitochondrial and extra-mitochondrial enzyme systems of heart cells are capable of persistent oscillations.