Sodium exchange in smooth muscle

Burnstock, G; Dewhurst, D.J.; Simon, Shirley E.

doi:10.1113/jphysiol.1963.sp007142

Cited by 31 publications

(15 citation statements)

References 28 publications

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“…In developing this technique it seemed that the proposition that an extra-EXTRACELLULAR MARKER cellular marker should never enter the cells placed too severe a constraint on the choice of molecules. Molecules which are large enough to meet this criterion such as [i3'I]serum albumin, equilibrate slowly with the extracellular water and exhibit kinetics which are substantially different from those of small molecules such as sodium (Burnstock, Dewhurst & Simon, 1963;Barr & Malvin, 1965). The kinetic method employed in this study only required the rate of equilibration with the extracellular water to be relatively fast in comparison with the rate of entry into the smooth muscle cells.…”

Section: Discussionmentioning

confidence: 99%

Distribution and kinetics of CoEDTA in smooth muscle, and its use as an extracellular marker

Brading¹,

Jones²

1969

The Journal of Physiology

144

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1. [(60)Co]EDTA has been evaluated as an extracellular marker in guinea-pig taenia coli and rabbit myometrium.2. The complex was found to be stable, non-toxic, convenient to use and had the advantage of being readily measured without interfering with the analysis of water and electrolyte contents.3. In both smooth muscles [(60)Co]EDTA distributed rapidly into a volume equivalent to that available to [(14)C]sorbitol and slightly greater than that available to inulin.4. The optimum concentrations of carrier required to effectively saturate any adsorption sites were 0.1 mM-CoEDTA for taenia coli and 1.0 mM for myometrium.5. [(60)Co]EDTA was distributed into a volume equivalent to the total water content of rabbit tendon, indicating that it was not excluded from connective tissue water.6. About 5% of the [(60)Co]EDTA taken up by smooth muscle in 15 minutes exhibited slow efflux kinetics. This property was also exhibited by [(14)C]sorbitol and has been reported for other extracellular markers.7. The efflux of 95% of [(60)Co]EDTA followed bulk diffusion kinetics for both taenia coli and myometrium.8. The simultaneous efflux of (24)Na indicated that 1-2% exchanged slowly while 98-99% of the (24)Na exchange could be described by bulk diffusion kinetics, similar to [(60)Co]EDTA. About 15% of this (24)Na was contained outside of the [(60)Co]EDTA space.9. More detailed studies involving the analysis of simultaneous efflux of [(60)Co]EDTA and (24)Na may help to locate and characterize the properties of the excess rapidly exchanging sodium (12-15 m-equiv/kg. wet wt.) in smooth muscle.

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Section: Discussionmentioning

confidence: 99%

Distribution and kinetics of CoEDTA in smooth muscle, and its use as an extracellular marker

Brading¹,

Jones²

1969

The Journal of Physiology

144

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“…In 127 mM-sodium 24 mM-potassium medium, these quantities become 244 and 36 Mlmoles and in 75 mM-sodium 75 mmpotassium medium, 146 Mmoles of each ion per g of dry weight. It is uncertain how rapidly the extracellular space equilibrates with the medium, and the process is probably not any simpler in auricles (Carslake & Weatherall, 1962) than in toad stomach, in which it has been studied more fully (Burnstock, Dewhurst & Simon, 1963). Therefore, any exact correction of the results in Table 3 would be speculative.…”

Section: Changes In Ionic Content Of Auriclesmentioning

confidence: 99%

Calcium in Relation to the Actions of Ouabain and Adrenaline on the Heart

Walker

Weatherall

1964

British Journal of Pharmacology and Chemotherapy

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Isolated pairs of rabbit auricles have been observed in media containing 6, 24 or 75 mm-potassium, with corresponding reductions in sodium concentration. In 24 mM-potassium, adrenaline restored beating and excitability, as did calcium chloride, but ouabain had no effect. In 75 mM-potassium, adrenaline had no effect; calcium chloride caused a contracture; ouabain had no direct effect, but auricles which had been beating in the presence of ouabain contracted promptly on transfer to 75 mM-potassium. Left auricles, which do not beat spontaneously, were less sensitive to calcium and to ouabain. The results showed a membrane stabilizing action of calcium and an action on muscular contraction, and suggested that cardiac glycosides acted by causing accumulation of calcium at the activator site in the tissue.

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“…2 and 3). Obviously it is impossible to conduct a continuous inflow experiment, but by serial counting of radioactivity of samples Burnstock, Dewhurst & Simon (1963) and Garrahan, Villamil & Zadunaisky (1965) reported that 95% of the total sodium in smooth muscle had exchanged with the tracer in the first few minutes. This rapid uptake agrees with the information revealed by our theoretical inflow graph.…”

Section: Discussionmentioning

confidence: 99%

Sodium Distribution in Mesenteric Arterial Wall of Rats with Hypertension Induced by Drinking Saline

1979

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1. Hypertension was induced in rats by substituting 2% (w/v) sodium chloride solution for drinking water. Sodium distribution in isolated mesenteric arterial wall was studied with the aid of 22Na, which was continuously washed out. Data were analysed by digital computer simulation without recourse to ancillary chemical measurements of extracellular space. 2. A three-compartment model consisting of (i) extracellular, (ii) intracellular and (iii) subcellular space was found to represent adequately the kinetics of 22Na. Transport rate constants were chosen as primary parameters describing intercompartmental sodium exchanges; the ratio of extra- to intra-cellular sodium compartments was calculated. 3. Results show the following significant changes in mesenteric arterial wall of salt-loaded hypertensive rats: (i) slowed sodium turnover; (ii) a decrease of the transport rate constant, which is presumed to reflect sodium movements from the intra- to the extra-cellular compartment; (iii) an increase of the transport rate constant, presumed to reflect sodium movements from the extra- to the intra-cellular compartment; (iv) a diminution of the extra- to intra-cellular compartment ratio for sodium. 4. The results suggest net movement of sodium into the cells; this change may be relevant to smooth muscle contraction and hence to the pathogenesis of blood pressure elevation in this model.

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Sodium exchange in smooth muscle

Cited by 31 publications

References 28 publications

Distribution and kinetics of CoEDTA in smooth muscle, and its use as an extracellular marker

Distribution and kinetics of CoEDTA in smooth muscle, and its use as an extracellular marker

Calcium in Relation to the Actions of Ouabain and Adrenaline on the Heart

Sodium Distribution in Mesenteric Arterial Wall of Rats with Hypertension Induced by Drinking Saline

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