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Tissue extract recovers cardiac calcium channels from 'run-down'
M Kameyama1, A Kameyama, T Nakayama
1National Institute for Physiological Sciences, Okazaki, Japan.
Pflugers Archiv : European Journal of Physiology
|August 1, 1988
Summary
Cardiac tissue extract prevents and restores L-type calcium channel activity in guinea-pig ventricular myocytes. This suggests a cytoplasmic protein maintains cardiac L-type calcium channel function.
Area of Science:
- Cardiology
- Molecular Biology
- Cell Physiology
Background:
- L-type calcium channels are crucial for cardiac function.
- Channel activity can be lost (run-down) after cell isolation.
Purpose of the Study:
- To investigate the effect of cardiac tissue extract on L-type calcium channel activity.
- To identify factors within the extract that modulate channel function.
Main Methods:
- Patch-clamp electrophysiology on guinea-pig ventricular myocytes.
- Preparation and fractionation of cardiac tissue homogenate.
- Assessing L-type calcium channel current run-down and recovery.
Main Results:
- Cardiac tissue extract prevented run-down of L-type calcium channel activity.
- The extract restored channel activity after run-down.
- The active factor(s) were heat-labile and trypsin-sensitive, with a molecular weight of 200-300 kDa.
Conclusions:
- A cytoplasmic protein(s) in cardiac tissue extract maintains L-type calcium channel activity.
- This protein factor is essential for preserving cardiac L-type calcium channel function.