Colorimetric Determination of Calcium with Ammonium Purpurate

Williams, M. B.; Moser, J. H.

doi:10.1021/ac60081a036

Cited by 66 publications

(13 citation statements)

References 3 publications

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“…Ca determination. A modification of the method described by Williams & Moser (1953) was used to determine the Ca content of our Ca-deficient solutions, and we obtained results similar to those of Miledi & Thies (1971). The Ca concentration of nominally Ca-free solutions ranged from 10-30 /M before the solutions were applied to the muscles, and they ranged from 40 to 50 /M after having been applied to the muscles for about half an hour.…”

Section: Methodssupporting

confidence: 56%

Effects of calcium and magnesium on the frequency of miniature end‐plate potentials during prolonged tetanization

Hurlbut¹,

Longenecker²,

Mauro³

1971

The Journal of Physiology

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1. End‐plate potentials (e.p.p.s) and miniature end‐plate potentials (min.e.p.p.s) were recorded intracellularly from the cutaneous pectoris nerve‐muscle preparation of the frog during prolonged stimulation at low frequencies (5/sec—50/sec). 2. When Ca was present in the bathing solution, the quantum content of the e.p.p. and the frequency of occurrence of the min.e.p.p.s gradually increased during the period of stimulation. During the first few minutes of stimulation, the min.e.p.p. frequency increased linearly with time, and the rate of increase was dependent on the Ca concentration of the bathing solution. However, Mg had no effect on this Ca‐dependent increase in min.e.p.p. frequency. 3. A large maintained increase in min.e.p.p. frequency also occurred during prolonged stimulation in solutions that contained no added Ca and 1‐2 m M‐EGTA. Under these conditions the increase in min.e.p.p. frequency was dependent on the Mg concentration of the bathing solution and was exponential in time. 4. It is suggested that the rise in min.e.p.p. frequency is caused by an accumulation of Ca or Mg ions in the nerve terminal, and it is suggested that these ions enter the terminal at relatively non‐specific sites distinct from the Ca‐specific sites that trigger the ‘phasic’ release of transmitter.

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Section: Methodssupporting

confidence: 56%

Effects of calcium and magnesium on the frequency of miniature end‐plate potentials during prolonged tetanization

Hurlbut¹,

Longenecker²,

Mauro³

1971

The Journal of Physiology

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“…The indicator was stabilized by dissolving it in a wateralcohol mixture as suggested by Williams. 12 …”

Section: Methodsmentioning

confidence: 99%

Acetyicholine and Electrolyte Metabolism in the Various Chambers of the Frog and Turtle Heart

Mazel

Holland

1958

Circulation Research

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Evidence has accumulated suggesting-ncetylcholine may be involved in initiation of the heart bent. Acetyleholine and electrolyte metabolism in the various chambers of the heart have been studied. The area of highest intrinsic rhythm (sinus) contained greater amounts of acetylcholine equivalents, true cholinesterase, choline acetylase and sodium; all of these decreasing in amount in areas of lower intrinsic rhythm. It is concluded that intrinsic rhythm may be directly correlated with overall acetylcholine metabolism and sodium content and inversely related to overall energy metabolism and potassium concentration.

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“…Electrolyte effects (11) There is competition between Na + and Ca ++ for the micelle [18,19]. Accordingly, the binding of Ca ++ is weakened by the addition of NaC1 as may be seen in Fig.…”

Section: Effect Of Suocactant Concentrationmentioning

confidence: 97%

“…Murexide (ammonium purpurate) forms a complex with Ca ++ resulting in a change in the visible absorption spectrum [11]. Figure I shows typical spectra.…”

Section: Measurement Of Free and Bound Calciummentioning

confidence: 99%

Binding of calcium ions to micelles ? a metallochromic indicator study

Miller

1989

Colloid & Polymer Sci

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Abstract:The complex formation of Ca ++ with murexide was investigated spectrophotometrically. In the presence of surfactants, such measurements can be used to determine the extent of binding of Ca ++ to the micelles. Experiments with secondary alkane sulphonate showed that there is competition between Na § and Ca + § for the micelles. Below the critical micelle concentration, no binding was observed.

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Colorimetric Determination of Calcium with Ammonium Purpurate

Cited by 66 publications

References 3 publications

Effects of calcium and magnesium on the frequency of miniature end‐plate potentials during prolonged tetanization

Effects of calcium and magnesium on the frequency of miniature end‐plate potentials during prolonged tetanization

Acetyicholine and Electrolyte Metabolism in the Various Chambers of the Frog and Turtle Heart

Binding of calcium ions to micelles ? a metallochromic indicator study

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