Tracer-diffusion in Liquids. IV. Self-diffusion of Calcium Ion and Chloride Ion in Aqueous Calcium Chloride Solutions<sup>1</sup>

Wang, Jui H.

doi:10.1021/ja01103a539

Cited by 84 publications

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“…In spite of these qualifications, our results suggest: (1) the facilitatory process evoked by ATP or oc-adrenaline action causes additional calcium discharge from the sarcoplasmic reticulum in association with the action potential; (2) during this facilitation, the relationship, QsR = fS, between facilitatory factor f and calcium content of the SR store, S, appears to be maintained; (3) the facilitatory effect (the increase of factor J) can be considerable, amounting at high () 2 /tM) ATP to a 14-fold enhancement of calcium discharge, and possibly more than this; (4) the build-up of facilitation in ATP media, which occurs with a half-time of 6-10 s, is somewhat slower than simple diffusion equilibration of ATP at heart cell surfaces (this is based on a comparison of the ratio of diffusion coefficients of calcium ions and ATP in aqueous media, of 2 1 (8 and 3-8 x 10 -6 cm2 s- ;Wang, 1953;Bowen & Martin, 1964) with the ratio of 3-5 = 7.7 s/2 2 s for the half-times (t, of build-up ofJ)/(t1 of rapid tension changes to + [Ca2+] steps), the latter, 2 2 s (±0-7 s, s.D), being obtained from fifteen trabeculae whose results were more closely analysed in this work); (5) results obtained with different calcium levels in ATP media (Fig. 5) suggest that the process of calcium-induced calcium release plays little part in the facilitatory event.…”

Section: Resultsmentioning

confidence: 99%

Receptor‐controlled Calcium Discharge in Frog Heart Cells

Niedergerke

Page

1989

Exp Physiol

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SUMMARYA brief account is given of previous work concerned with the effects which ATP (P2-'purinergic') and a-adrenaline receptors have on the activity of the sarcoplasmic reticulum (SR) in frog heart atrial cells. More recent experiments made with single atrial trabeculae are also described which suggest, among other things, that ATP and a-adrenaline receptors both facilitate the process by which an action potential induces SR calcium discharge in atrial heart cells. The facilitatory effect involved is considerable; at high (.> 2 /iM) ATP doses, SR calcium discharge seems to be increased about 14-fold and, quite possibly, more than this. Results obtained with different levels of [Ca2+]. during ATP action suggest that the process of calciuminduced calcium release plays little part in the facilitatory process. Its putative mechanism is briefly discussed.

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Section: Resultsmentioning

confidence: 99%

Receptor‐controlled Calcium Discharge in Frog Heart Cells

Niedergerke

Page

1989

Exp Physiol

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“…(5), assuming a radius of 0 05 cm and the efflux rate constant for component 1 given in Table 4. Do was calculated from the self-diffusion coefficient for CaCl2 in aqueous solution at 25 0C (0-78 x 10-cm2/sec; Wang, 1953) and the equation (Neville, 1979): R = ,I T2/'12T, where R is the ratio between the diffusion constants at temperatures T1 and T2 (in OK) and the ij and fl2 are the viscosities of water at the two temperatures.…”

Section: Resultsmentioning

confidence: 99%

Calcium fluxes in mouse mammary tissue in vitro: intracellular and extracellular calcium pools

Neville

Peaker

1982

The Journal of Physiology

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SUMMARY1. The total Ca content of the mammary gland increased from about 2 to 12 #smole/g tissue during the transition from pregnancy to lactation in the mouse.In tissue from lactating mice at least two thirds of the total Ca exchanged with external Ca in 6 hr. There was little non-exchangeable Ca in tissues from pregnant mice.2. At 37 'C the time courses of influx and efflux of 45Ca in lactating tissues could be analysed by assuming three exponential components with rate constants of about 03, 006 and 0005 min-and containing, respectively, 1-7, 1-5 and 4-7 mole 45Ca/g tissue at the steady state.3. The rapidly effluxing component showed the time-and temperature-dependence characteristic of bulk-phase-limited diffusion through the extracellular space. The diffusion coefficient was about one quarter of the self-diffusion coefficient of Ca in aqueous solution, consistent with a tortuosity factor of about 2. A portion of the Ca in this component was displaced by La3+. The amount remaining in the presence of 3 mM-La3+ was close to that expected for free extracellular Ca. The rapid component was therefore interpreted as originating from an extracellular compartment containing both free and bound Ca.4. The rate of efflux of the intermediate component was slowed by a factor of ten when the temperature was decreased from 37 to 0C giving a Q10 of 2-7, expected for membrane transport. The slow component present at 37 'C was not displaced by EGTA or La3+, suggesting that it is not localized extracellularly. It was not apparent in the 0 'C efflux curves. 5. The biphasic time course of uptake of ionophore (A23187)-releasable 45Ca in particulate fractions obtained by homogenization and centrifugation of tissues which had been incubated with the isotope was consistent with the hypothesis that the two slower components of 45Ca flux originate from intracellular compartments. Mitochondrial uptake probably did not contribute significantly to Ca exchange in these tissues.6. 45Calcium fluxes in mammary tissues from pregnant mice also showed three

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“…D' is thus only I of the coefficient in free solution, and about i of what might have been assumed to hold for diffusion in the extracellular space. (The coefficient of self-diffusion of labelled Ca2+ ions in aqueous 10 mm and 70 mM-CaCl2 solution at 250 C has been determined to be about 7-8 x 10-6 cm2/ sec (Wang, 1953). )…”

Section: R Niedergerkementioning

confidence: 99%

The rate of action of calcium ions on the contraction of the heart

Niedergerke¹

1957

The Journal of Physiology

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Calcium ions are known to facilitate the contraction of heart muscle (e.g. Niedergerke, 1956). The effect produced by a change in the external Ca concentration develops and subsides rapidly and may therefore be presumed to take place at the cell surface, yet quantitatively the rates of onset and decay appear to be too slow to be explained entirely by simple diffusion through the extracellular fluid spaces. It was of interest to obtain further evidence about the cellular localization of the Ca effect. For this purpose the rate at which the facilitating action develops or declines was compared with the rate at which labelled Ca ions are taken up by, or released from the tissue. METHODSStrips were dissected from a circular section of the wall of frog's ventricle (Rana temporaria and esculenta) (Dale, 1932). The tissue was cut into cylindrical portions of a given diameter (varying in different strips from 0 4 to 1-1 mm) following as far as possible along the main direction of the fibres within the syncytium. Strips were only employed if the variations in diameter along the length did not exceed about 10%. In one experiment a thin auricle strip was used. Auricle strips can be dissected without causing excessive damage since regions can be found where the fibres run practically parallel. However, these strips, if in good condition, beat spontaneously at a fairly high rate (about 20/min) so that they are not entirely suitable for the present investigations. Apparatus, Ringer bath and the composition of Ringer's fluid were similar to those described earlier (Niedergerke, 1956).Tracer method. Ca output was measured by a procedure similar to that used by Harris (1957) on the frog's sartorius muscle. Strips were immersed during the night in a 45Ca-labelled Ringer's solution. The tracer was then soaked out into a series of small volumes (1 or 2 ml.) of inactive Ringer's fluid. Strips were fixed with slight stretch on a holder made of thin stainless steel wire. 1 ml. samples of the 'soaking out' fluid were dried on planchettes and counted with an endwindow Geiger counter. In order to estimate the amount of labelled Ca remaining inside the tissue at the end of the 'soaking out' time, the tissue was transferred to a platinum planchette and dissolved in concentrated nitric acid so as to spread the 4"Ca evenly over the area of the planchette. The residue was incinerated at 5000 C. Before comparing the radioactivity of the ash with that of the dried portion of saline, a correction was applied to allow for the reduction due to absorption of radiation by the solid residue of the saline solution. The ash had negligible weight.

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Tracer-diffusion in Liquids. IV. Self-diffusion of Calcium Ion and Chloride Ion in Aqueous Calcium Chloride Solutions¹

Cited by 84 publications

References 0 publications

Receptor‐controlled Calcium Discharge in Frog Heart Cells

Receptor‐controlled Calcium Discharge in Frog Heart Cells

Calcium fluxes in mouse mammary tissue in vitro: intracellular and extracellular calcium pools

The rate of action of calcium ions on the contraction of the heart

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Tracer-diffusion in Liquids. IV. Self-diffusion of Calcium Ion and Chloride Ion in Aqueous Calcium Chloride Solutions1

Cited by 84 publications

References 0 publications

Receptor‐controlled Calcium Discharge in Frog Heart Cells

Receptor‐controlled Calcium Discharge in Frog Heart Cells

Calcium fluxes in mouse mammary tissue in vitro: intracellular and extracellular calcium pools

The rate of action of calcium ions on the contraction of the heart

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Tracer-diffusion in Liquids. IV. Self-diffusion of Calcium Ion and Chloride Ion in Aqueous Calcium Chloride Solutions¹