What question did this study set out to answer?

To investigate whether fast sodium current (INa) plays a direct role in triggering excitation-contraction coupling in cat ventricular myocytes.

Fast sodium influx provides an initial step to trigger contractions in cat ventricle

View Full Paper

Ask AI

Bookmark

To investigate whether fast sodium current (INa) plays a direct role in triggering excitation-contraction coupling in cat ventricular myocytes.
Assessed membrane currents and cell shortening (reduction in cell length, delta L) in isolated cat ventricular myocytes subjected to voltage steps from -70 to -40 mV across various holding potentials.
Tested the effects of ion channel modulators and inhibitors, including 10 microM nifedipine, 1-10 microM ryanodine, 1-10 microM saxitoxin, 0.1-1.0 mM cadmium, and 3-10 nM Anthopleura toxin A.
Nifedipine (10 microM) completely abolished calcium currents but only reduced cell shortening (delta L) by approximately 15%, whereas the remaining contraction was abolished by saxitoxin, ryanodine, and cadmium.
Anthopleura toxin A slowed INa inactivation, increased maximal delta L, and produced a +7-mV shift in the delta L-holding potential relationship, an effect prevented by saxitoxin preexposure.

Population

Cat ventricular myocytes

Intervention

Voltage steps and pharmacological agents (nifedipine, ryanodine, saxitoxin, Cd2+, Anthopleura toxin A)

Outcome

Transient contraction (reduction in cell length, delta L) and Na+ current (INa)surrogate

Fast sodium influx provides an initial step to trigger contractions in cat ventricular myocytes, independent of calcium current.

No takes yet. Share an insight, caveat, or question.

INa may trigger contractions independent of ICa in feline myocytes; leaves open relevance to human EC coupling or clinical translation.

Vites et al. (1996) studied this question.

View Full Paper

Ask AI

Bookmark