What is the clinical evidence from this study?

Study design: Other. Intervention: Isoproterenol (isoprenaline) vs. Basal conditions. Primary outcome: Kinetics of voltage-dependent inactivation of native cardiac L-type Ca(2+) currents.

What question did this study set out to answer?

To characterize the kinetic properties and voltage sensitivity of native cardiac L-type calcium channel inactivation in isolated ventricular myocytes.

November 28, 2002The Journal of PhysiologyOpen Access

Voltage‐dependent inactivation of l‐type ca2+ Currents in Guinea‐Pig Ventricular Myocytes

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Key result

Beta-adrenergic stimulation with isoproterenol altered the reaction of native cardiac L-type Ca(2+) channels to membrane voltage, reducing inactivation compared to basal conditions.

Population

Guinea-pig isolated ventricular myocytes

Comparison

Isoproterenol and varying membrane voltages vs Basal conditions

Design

Preclinical

Authors

IFIan FindlayUniversité de Tours

Discussion

Member takes

Implication

No immediate clinical implications; hypothesis-generating for beta-adrenergic modulation of L-type Ca channel inactivation in vivo.

Key Points

To characterize the kinetic properties and voltage sensitivity of native cardiac L-type calcium channel inactivation in isolated ventricular myocytes.
Recorded whole-cell currents from isolated guinea-pig ventricular myocytes using patch-clamp electrophysiology.
Isolated voltage-dependent inactivation from calcium-dependent mechanisms by substituting extracellular calcium with magnesium and measuring outward currents under basal conditions and during isoproterenol application.
Voltage-dependent inactivation accelerated from a slow monophasic decay at -30 mV to a maximal rapid biphasic decay at +20 mV, where the fast time constant was tau(f) ≈ 30 ms (70% of amplitude) and the slow time constant was tau(s) ≈ 300 ms.
Isoproterenol induced a large time-independent outward current during depolarization, transforming the basal sigmoidal availability curve into a U-shaped availability-voltage profile.

Structured PICO

Population

Guinea-pig isolated ventricular myocytes used to study the kinetics of voltage-dependent inactivation of native cardiac L-type Ca(2+) currents.

Intervention

Isoproterenol (isoprenaline) and varying membrane voltages

Comparator

Basal conditions

Outcome

Kinetics of voltage-dependent inactivation of native cardiac L-type Ca(2+) currentssurrogate

Beta-adrenergic stimulation with isoproterenol alters the voltage-dependent inactivation of cardiac L-type Ca2+ channels, allowing depolarization to reduce inactivation.

Cite This Study

Ian Findlay (2002) studied this question. Isoproterenol (isoprenaline) vs. Basal conditions was evaluated on Kinetics of voltage-dependent inactivation of native cardiac L-type Ca(2+) currents. Beta-adrenergic stimulation with isoproterenol altered the reaction of native cardiac L-type Ca(2+) channels to membrane voltage, reducing inactivation compared to basal conditions.

synapsesocial.com/papers/6a75a753ef3d015f2ddd8087 https://doi.org/10.1113/jphysiol.2002.029637

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Voltage‐dependent inactivation of l‐type ca2+ Currents in Guinea‐Pig Ventricular Myocytes

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Voltage‐dependent inactivation of l‐type ca2+ Currents in Guinea‐Pig Ventricular Myocytes

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider