Electrophysiology of guinea-pig myenteric neurons correlated with immunoreactivity for calcium binding proteins.
Experiments were undertaken to define the electrophysiological characteristics and shapes of neurons in the myenteric plexus of the guinea-pig ileum that are immunoreactive for calcium binding proteins. Recordings were made from the neurons with intracellular microelectrodes containing a mixture of the fluorescent dye Lucifer yellow and KCl solution. The neurons studied were filled with Lucifer yellow so that they could be re-identified after processing the tissue to reveal immunoreactivity for either the calcium binding protein (CaBP), spot 35 protein, or vitamin D-dependent CaBP. Neurons were characterized as being AH-neurons, in which each action potential is followed by a prolonged after-hyperpolarization (greater than 4 s), or S-neurons, in which the prolonged after-hyperpolarizations were not observed and focal stimulation of internodal strands evoked fast excitatory synaptic potentials. S-neurons were never immunoreactive for the CaBPs (108 cells), but most AH-neurons (62 of 74) were immunoreactive. Immunoreactive and non-immunoreactive AH-neurons were indistinguishable on the basis of their electrophysiological properties or their shapes (all the AH-neurons were Dogiel type II in shape, i.e. smooth soma and many long processes). The S-neurons had a variety of shapes, but none could be classified as Dogiel type II. It is concluded that most AH-neurons are immunoreactive for calcium binding proteins, and that these proteins are restricted to AH-neurons.
Iyer
V
V
Centre for Neuroscience, School of Medicine, The Flinders University of South Australia, Bedford Park.
Bornstein
J C
JC
Costa
M
M
Furness
J B
JB
Takahashi
Y
Y
Iwanaga
T
T
D000818:Animals; D002135:Calcium-Binding Proteins / Q000276:immunology*; D004594:Electrophysiology; D006168:Guinea Pigs; D007150:Immunohistochemistry; D007546:Isoquinolines; D009197:Myenteric Plexus / Q000166:cytology / Q000276:immunology / Q000502:physiology*; D009474:Neurons / Q000145:classification / Q000276:immunology / Q000502:physiology*
D002135:Calcium-Binding Proteins; D007546:Isoquinolines; C017475:lucifer yellow