Electron probe analysis of sodium and other elements in hypertrophied and sodium-loaded smooth muscle.

Junker, James L.; Wasserman, A. J.; Berner, P F; Somlyo, Andrew P.

doi:10.1161/01.res.54.3.254

Cited by 20 publications

(28 citation statements)

References 33 publications

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“…The method originally was developed for rat tail artery, 6 but it has been used successfully in other preparations, including aorta 13 and portal vein. 14 In rabbit portal vein, the decline in the intracellular sodium content during 30 to 120 minutes in cold, lithium-substituted, sodium-free solution, as measured by the electron microprobe, is similar to that seen in rat tail artery under similar conditions. 13 However, with the microprobe there is a great deal of cell to cell variation in the sodium signal, with outlying high sodium signals in many cells.…”

Section: Discussionsupporting

confidence: 55%

Direct measurement of sodium influx in vascular smooth muscle. Stimulation by aldosterone.

Menard¹,

Friedman²

1985

Hypertension

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SUMMARY The influx of 22Na into the smooth muscle cells of incubated rat tail arteries was measured directly, in the presence and absence of 2.8 x 10" 7 M D-aldosterone. During the analysis, extracellular 22 Na and 23 Na were removed by incubation of the tissue in sodium-free lithium-substituted physiological salt solution at less than 3 °C. Aldosterone increased the influx rate coefficient by 10% (0.104 ± 0.004 [SE] min" 1 , n = 13, vs 0.095 ± 0.003 [SE] min" 1 , n = 13 without aldosterone; p < 0.01) but did not significantly reduce the sodium content. We conclude from direct measurements that aldosterone acts to increase the influx of sodium in incubated tail arteries from normal rats; we conclude from measurements of the sodium influx and sodium content that aldosterone also acts to increase the efflux of sodium in this preparation. (Hypertension 7: 873-878, 1985) KEY WORDS • sodium transport • sodium permeability • corticosterone

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Section: Discussionsupporting

confidence: 55%

Direct measurement of sodium influx in vascular smooth muscle. Stimulation by aldosterone.

Menard¹,

Friedman²

1985

Hypertension

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“…is significantly higher (P < 0-001) in the main pulmonary artery, with its abundant central s.r., than in portal vein (276 and 268 mmol/kg dry wt. : Bond et al 1984b;Junker, Wasserman, Berner & Somlyo, 1984, as measured by large defocused probes), which contains much less central s.r. The existence of two populations among microregions of main pulmonary artery is also indicated by the skewed distribution of the phosphorus concentrations (Fig.…”

Section: Contraction Of Rb-containing Smooth Musclementioning

confidence: 99%

Calcium release by noradrenaline from central sarcoplasmic reticulum in rabbit main pulmonary artery smooth muscle.

Kowarski¹,

Shuman²,

Somlyo³

et al. 1985

The Journal of Physiology

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109

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SUMMARY1. The subcellular composition of relaxed and noradrenaline-contracted rabbit main pulmonary artery smooth muscle cells was measured by electron probe X-ray microanalysis of cryosections of rapidly frozen tissue. Some of the preparations were made permeable with saponin and exposed to a known free Ca ion concentration, rapidly frozen, freeze-substituted, and also analysed by electron probe X-ray microanalysis.2. 98 % of intracellular K could be replaced by Rb. This was done to remove the K peak that partially overlaps the Ca peak in the X-ray spectra. 8. Mitochondrial [Ca] was not significantly different in relaxed and contracted tissues (P > 0-05). Mitochondrial [Ca] was 2-2 + 0-24 mmol/kg dry wt. (mean + S.E. of mean; n = 163), combining data from relaxed and contracted tissues. K was replaced by Rb in mitochondria to the same extent as in the cytoplasm.9. In saponin-treated preparations exposed to 1 AM-free Ca ions and 5 mM-oxalate, the s.r. lumen was swollen and contained Ca deposits. These deposits occurred at sites apposed as well as not apposed to the plasma membrane (junctional and central s.r.), amidst cytoplasm that contained little Ca by comparison. Large deposits of calcium oxalate adjacent to the nucleus were frequently observed, in a distribution similar to that of the Golgi apparatus.10. We conclude that: (a) the central s.r. can accumulate large amounts of Ca, (b) noradrenaline releases Ca from the central s.r., as well as from the junctional s.r., (c) noradrenaline releases Ca from the central s.r. in the presence of normal (1 2 mM) extracellular Ca, (d) the release of Ca from central s.r. is sufficient to cause maximal contraction, (e) the relative sizes of the central s.r. and mitochondrial Ca pools in relaxed tissue are about 20: 1.

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“…First, the values derived for [Na], were three to four times higher, even with maximal allowance for cell water. 9 Second, [Na], did not increase with stretch as observed with chemical and electrochemical methods." Third, a variable amount of Na appeared to be removed from cells by a 2°C wash with Li-substituted medium.…”

Section: Discussionmentioning

confidence: 80%

“…9 The ion exchange method is based on the essentially passive distribution of Li and its close steric relation to Na. 10 This method has permitted the separation of cell Na into free and constrained components and yielded values for [Na], ranging from 10 to 15 mM.…”

Section: Discussionmentioning

confidence: 99%

Prehypertensive changes in sodium transport induced by deoxycorticosterone acetate in incubated rat tail artery.

Friedman¹,

McIndoe²,

Tanaka³

1986

Hypertension

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SUMMARY The transport and distribution of sodium, potassium, and water were examined in tail arteries of rats treated with deoxycorticosterone acetate (DOCA)-saline for 10 days, a time that marks the earliest onset of a rise of blood pressure in the strain (Wistar) used. The arteries were incubated for more than 20 hours to ensure that any change observed was sufficiently built in so that it could not readily be washed out. Three distinct changes were observed. First, the steady state transmembrane sodium gradient (operationally [NaVfNa],) was increased. Second, the amount of sodium excluded from participation in the sodium gradient, and hence probably bound, was increased. Third, after prolonged potassium depletion, the ouabain-insensitive loss of cell water and sodium that follows the readmittance of potassium was increased. These results suggest that fundamental embedded changes in sodium transport occur well before the blood pressure rises in response to DOCA-saline. (Hypertension 8: 592-599, 1986) KEY WORDS • hypertension deoxycorticosterone acetate sodium cell water vascular smooth muscle S TRUCTURAL changes have long been known to play an important role in the development and perhaps the initiation of the hypertensive process. 1 In general, only the physical aspects of these changes as they determine the geometry and hence the reactivity of the vascular wall have been denned. It is clear, however, that structural changes include the chemical configuration of the cell membrane and the cytoplasm and that, as determinants of ion permeability and distribution, these warrant equal consideration. Such changes should be sufficiently embedded to be discernible in the blood vessel maintained in vitro under artificial conditions. The present study was undertaken to examine this possibility insofar as it affects the transport and distribution of Na in the tail artery taken from rats treated with deoxycorticosterone acetate (DOCA)-saline for 10 days and incubated in various modified physiological salt solutions for 18 to 24 hours before analysis. Received April 16, 1985; accepted January 5, 1986. Materials and Methods Adult male rats of an inbred Wistar strain (Charles River Canada, Montreal, Quebec), weighing 300 g or more were used throughout in batches of 18 or 36 rats for each experiment. These batches were unilaterally nephrectomized under pentobarbitone sodium anesthesia; 3 to 7 days later, half of each batch was set aside as controls and half were injected subcutaneously with 0.5 ml of saline containing 12.5 mg of DOC A as a microcrystalline suspension. A second and third injection of 6.25 mg each were given on Days 4 and 7. Vehicle alone was administered to controls on the same schedule to ensure equal handling. The DOCAtreated rats were given 1 % saline as drinking water so that the effective agonist was the DOCA-saline combination. At the 1% level, saline alone has no significant eifect on blood pressure or on conventional indices of Na transport.

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Electron probe analysis of sodium and other elements in hypertrophied and sodium-loaded smooth muscle.

Cited by 20 publications

References 33 publications

Direct measurement of sodium influx in vascular smooth muscle. Stimulation by aldosterone.

Direct measurement of sodium influx in vascular smooth muscle. Stimulation by aldosterone.

Calcium release by noradrenaline from central sarcoplasmic reticulum in rabbit main pulmonary artery smooth muscle.

Prehypertensive changes in sodium transport induced by deoxycorticosterone acetate in incubated rat tail artery.

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