What question did this study set out to answer?

This research aims to explore the mechanisms underlying premature extra-activation potentiation of atrial contractions in the guinea-pig heart.

January 1, 1968The Japanese Journal of PhysiologyOpen Access

Premature Extra-Activation Potentiation of Contraction in the Guinea-Pig Atrium

Q: What is the clinical evidence from this study?

Population: Normal cardiac physiology (guinea-pig atrium) (n=27). Intervention: Premature extra-activation (electrical stimulation) vs. Regular basal stimulation. Primary outcome: Isometric contractile tension and transmembrane potentials.

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Key result

Premature extra-activation in guinea-pig atrial muscle produced marked potentiation of contraction, primarily caused by enhancement of the positive inotropic effect of activation.

Population

Isolated guinea-pig atrium

Comparison

Continual premature extra-activations vs Regular contraction without extra-activations

Design

Preclinical

Authors

MGMasayosi GOTOKyushu University YSYasuji SakamotoUniversity of Occupational and Environmental Health Japan HKHiroshi KawataHigh Energy Accelerator Research Organization

Discussion

Member takes

Implication

No immediate clinical implications for atrial arrhythmias; leaves open mechanistic studies on calcium-dependent potentiation in humans.

Key Points

This research aims to explore the mechanisms underlying premature extra-activation potentiation of atrial contractions in the guinea-pig heart.
Isolated guinea-pig atrium used to measure isometric tension development and contraction dynamics.
Analyzed effects of different solutions (Ca++-excess, caffeine, hypertonic, and hypotonic solutions) on potentiation.
Investigated relationship between frequency-strength and degree of activation.
Continual premature extra-activations enhanced peak tension without changing contraction duration.
PIEA showed marked enhancement while NIEA had a slight increase during extra-activation potentiation.
Calcium levels crucially influenced potentiation; caffeine and hypertonic solutions inhibited it while Ca++ absence enhanced it.

Structured PICO

Population

27 experiments using auricular muscle strips freshly isolated from the left atrium of guinea-pig hearts to study the mechanisms of premature extra-activation potentiation.

Intervention

Continual premature extra-activations (extra-stimuli)

Comparator

Regular contraction without extra-activations

Outcome

Rate of isometric tension development and peak tension of regular contractionsurrogate

Premature extra-activations potentiate contraction in guinea-pig atria, likely due to changes in calcium release and uptake by tubular systems.

Limitations

Grid electrodes were found to be unsuitable because of greater stimulation artifacts and adrenergic/cholinergic electro-release effects on contractility.

Cite This Study

GOTO et al. (1968) studied Normal cardiac physiology (guinea-pig atrium) (n=27). Premature extra-activation (electrical stimulation) vs. Regular basal stimulation was evaluated on Isometric contractile tension and transmembrane potentials. Premature extra-activation in guinea-pig atrial muscle produced marked potentiation of contraction, primarily caused by enhancement of the positive inotropic effect of activation.

synapsesocial.com/papers/6a6ac05b3e46b6df0af2dc37 https://doi.org/10.2170/jjphysiol.18.238

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Premature Extra-Activation Potentiation of Contraction in the Guinea-Pig Atrium

Discussion

Member takes

Implication

Key Points

Structured PICO

Limitations

Cite This Study

Premature Extra-Activation Potentiation of Contraction in the Guinea-Pig Atrium

Discussion

Member takes

Implication

Key Points

Structured PICO

Limitations

Cite This Study

Also Consider

Also Consider