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Investigate calcium-accumulating properties in fragmented frog sarcoplasmic reticulum and determine whether caffeine primarily inhibits calcium uptake or promotes calcium release.

May 1, 1970The Journal of Biochemistry

Some Properties of Fragmented Frog Sarcoplasmic Reticulum with Particular Reference to Its Response to Caffeine*

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Investigate calcium-accumulating properties in fragmented frog sarcoplasmic reticulum and determine whether caffeine primarily inhibits calcium uptake or promotes calcium release.
Fractionated frog skeletal muscle microsomes into heavy (1,200–7,000×g) and light (7,000–54,500×g) sarcoplasmic reticulum preparations.
Measured calcium uptake kinetics in the presence of an ATP regenerating system across varying concentrations of ATP, Mg²⁺, oxalate, and inorganic phosphate.
Evaluated calcium release kinetics triggered by caffeine and thymol across different temperatures, fractions, and in the presence of procaine.
Calcium-accumulating capacity typically measured 160–200 mμmoles Ca/mg protein with a binding constant of 3–5×10⁶ M⁻², reaching nearly 300 mμmoles Ca/mg protein in highly caffeine-sensitive preparations.
Caffeine induced rapid calcium release preferentially in the heavier microsomal fraction and at lower temperatures, which was counteracted by procaine.
Thymol exhibited the same calcium-releasing mechanism as caffeine but demonstrated approximately thirty times greater potency.

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Implication

In vitro study demonstrates rapid calcium release induced by caffeine in frog sarcoplasmic reticulum, indicating caffeine acts as a calcium releaser rather than an uptake inhibitor.

Cite This Study

Yasuo Ogawa (1970) studied this question.

synapsesocial.com/papers/6a89b5e8b1e5d05ea8ec81b0 https://doi.org/10.1093/oxfordjournals.jbchem.a129295

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Implication

In vitro study demonstrates rapid calcium release induced by caffeine in frog sarcoplasmic reticulum, indicating caffeine acts as a calcium releaser rather than an uptake inhibitor.

Some Properties of Fragmented Frog Sarcoplasmic Reticulum with Particular Reference to Its Response to Caffeine*

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Discussion

Implication

Cite This Study

Some Properties of Fragmented Frog Sarcoplasmic Reticulum with Particular Reference to Its Response to Caffeine*

Key Points

Discussion

Implication

Cite This Study

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