What question did this study set out to answer?

To identify the specific delayed rectifier potassium current component inhibited by lanthanum and measure its electrostatic screening effects on cardiac sarcolemmal membranes.

December 1, 1990AJP Heart and Circulatory Physiology

Lanthanum blocks a specific component of IK and screens membrane surface change in cardiac cells

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Population

Isolated guinea pig ventricular myocytes

Design

Preclinical

Authors

MSMichael C. SanguinettiElectrophysiology NJNancy K. JurkiewiczUnited States Military Academy

Discussion

Member takes

Implication

May enable selective IK.r studies in animal models; leaves open human cardiac translation.

Key Points

To identify the specific delayed rectifier potassium current component inhibited by lanthanum and measure its electrostatic screening effects on cardiac sarcolemmal membranes.
Performed whole-cell voltage-clamp recordings on isolated guinea pig ventricular myocytes exposed to varying lanthanum concentrations.
Screened the effects of lanthanum against known current blocker E-4031 and calcium displacement.
Calculated outer surface charge density and binding constants using a modified Gouy-Chapman equation.
Lanthanum concentrations at or above 1 µM selectively and completely blocked the rapid delayed rectifier potassium current (IK.r), leaving only the slow component (IK.s) intact.
Lanthanum at 10 µM to 1 mM induced a positive shift in the voltage activation curve of IK.s via electrostatic surface charge screening.
Mathematical modeling estimated an external resting surface potential of -19 mV in 1.8 mM Ca2+, an equilibrium binding constant of 10.7 mM⁻¹, and a 22 Å minimum spacing between surface charges.

Structured PICO

Population

Isolated guinea pig ventricular myocytes

Intervention

Lanthanum (La3+) (≥1 microM and 10 microM-1 mM)

Outcome

Effect on delayed rectifier outward K+ current (IK), specifically IK.r and IK.ssurrogate

Lanthanum specifically blocks the rapidly activating delayed rectifier K+ current (IK.r) and alters the activation curve of IK.s in guinea pig ventricular myocytes.

Cite This Study

Sanguinetti et al. (1990) studied this question.

synapsesocial.com/papers/6a971c58a45595e5080e4e86 https://doi.org/10.1152/ajpheart.1990.259.6.h1881

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Lanthanum blocks a specific component of IK and screens membrane surface change in cardiac cells

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Lanthanum blocks a specific component of IK and screens membrane surface change in cardiac cells

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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