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Low-threshold current is major calcium current in chick ventricle cells
1Department of Anatomy and Cell Biology, Emory University Health Sciences Center, Atlanta, Georgia 30322.
The American Journal of Physiology
|May 1, 1989
Summary
Chick embryo heart cells exhibit significant T-type calcium current (IT), which is larger than L-type (IL) and contributes more to the overall calcium current (ICa) in developing cardiac tissue.
Area of Science:
- Cardiology
- Developmental Biology
- Electrophysiology
Background:
- Cardiac myocytes from embryonic chick ventricles are a model for studying cardiac ion channel function.
- Calcium currents (ICa) are crucial for cardiac excitation-contraction coupling.
Purpose of the Study:
- To characterize the T-type (IT) and L-type (IL) calcium current components in 14-day-old embryonic chick ventricular myocytes.
- To compare the relative contribution of IT and IL to the total ICa.
Main Methods:
- Whole-cell patch-clamp analysis was performed on isolated ventricular myocytes.
- Pharmacological agents (D600, Ni2+) and voltage-dependent properties were used to differentiate IT and IL.
- IT was calculated by subtracting IL from total ICa.
Main Results:
- Two distinct calcium current components, IT and IL, were identified.
- IT demonstrated a greater current density compared to adult cardiac tissue and was larger than IL.
- IT was the predominant contributor to the total ICa in this preparation.
Conclusions:
- Embryonic chick ventricular myocytes possess a substantial IT component, exceeding that found in adult tissues.
- The findings highlight the significant role of IT in embryonic cardiac electrophysiology.