Responsiveness to ATP with an increase in intracellular free Ca2+ is not a distinctive feature of calbindin-D28 immunoreactive neurons in myenteric ganglia.
The aim of this study was to test the hypothesis that ATP elevates cytosolic free Ca2+ levels ([Ca2+]i) in myenteric neurons expressing the Ca2+ binding protein, calbindin-D28. A laser microbeam marked the location of cultured neurons on coverslips and provided unequivocal relocation of ATP-responsive neurons after immunocytochemistry. All myenteric multipolar neurons displayed ATP Ca2+ transients, and 42% also expressed calbindin-D28 reactivity. Statistical analysis of the kinetics and shape of ATP Ca2+ transients revealed no differences between calbindin and non-calbindin neurons. The identity of other responsive neurons is unknown. Less than 8% of ganglion cells with ATP Ca2+ transients were immunopositive for the glial protein S-100. We conclude that one of the actions of ATP in myenteric ganglia is to increase [Ca2+]i which may activate gKCa leading to membrane hyperpolarization in AH, Dogiel Type II neurons expressing calbindin-D28. An efficient buffering mechanism for handling large purinergic Ca2+ loads is a common feature of all types of myenteric ganglion cells.
Christofi
F L
FL
Department of Anesthesiology, College of Medicine, Ohio State University, Columbus 43210, USA.
Guan
Z
Z
Lucas
J H
JH
Rosenberg-Schaffer
L J
LJ
Stokes
B T
BT
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D064026:Calbindins; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D006168:Guinea Pigs; D009197:Myenteric Plexus / Q000187:drug effects* / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000032:analysis*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000032:analysis*
D064026:Calbindins; D009419:Nerve Tissue Proteins; D064030:S100 Calcium Binding Protein G; D000255:Adenosine Triphosphate; D002118:Calcium