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Ryanodine sensitive calcium release channel from left ventricle, septum, and atrium of canine heart
1University of North Carolina at Chapel Hill 27599-7260.
Insights
Canine heart ryanodine receptors, calcium release channels, show similar function across different regions. This suggests functionally related, if not identical, channels are present in the left ventricle, septum, and atrium.
Area of Science:
- Cardiovascular Physiology
- Molecular Cardiology
- Ion Channel Research
Background:
- The ryanodine receptor is a critical calcium release channel in cardiac muscle.
- Investigating regional differences in cardiac ryanodine receptor function is essential for understanding excitation-contraction coupling.
Purpose of the Study:
- To determine if functionally distinct forms of the ryanodine-sensitive calcium release channel exist in different regions of the canine heart.
- To compare the characteristics of ryanodine receptors from the left ventricular free wall, interventricular septum, and atrium.
Main Methods:
- Isolation of membranous fractions enriched in ryanodine binding activity from specific canine heart regions.
- Purification of ryanodine receptors (RyR) using sucrose density gradient centrifugation after detergent solubilization.
- Measurement of single channel currents via reconstitution of purified RyR into planar lipid bilayers.
Main Results:
- Ryanodine-sensitive Ca2+ release channels from the left ventricular free wall, interventricular septum, and atrium exhibited identical [3H]ryanodine binding.
- Single channel characteristics of the ryanodine receptors were consistent across all three examined cardiac regions.
Conclusions:
- The left ventricular free wall, septum, and atrium of the canine heart likely express functionally related, if not identical, ryanodine receptor/Ca2+ release channels.
- These findings suggest a conserved role for ryanodine receptors in calcium handling across different regions of the canine heart.
Objective:
The aim was to consider the possibility that functionally distinct forms of the ryanodine sensitive calcium release channel are expressed in different regions of heart.
Methods:
Membranous fractions enriched in ryanodine binding activity were isolated from canine left ventricular free wall, interventricular septum, and atrium. Ryanodine receptors (RyR) were purified by sucrose density gradient centrifugation, following solubilisation of sarcoplasmic reticular membranes with the detergent Chaps. Single channel currents were measured, upon reconstitution of sarcoplasmic reticular vesicles and the purified RyR into planar lipid bilayers.
Results:
Ryanodine sensitive Ca2+ release channels from three different regions of canine heart displayed the same [3H]ryanodine binding and single channel characteristics.
Conclusions:
The left ventricular free wall, septum, and atrium of canine heart may express functionally related, if not identical, ryanodine receptor/Ca2+ release channels.