Purinergic Ca2+ signaling in myenteric neurons via P2 purinoceptors

1997 ◽  
Vol 272 (3) ◽  
pp. G463-G473 ◽  
Author(s):  
F. L. Christofi ◽  
Z. Guan ◽  
J. D. Wood ◽  
L. V. Baidan ◽  
B. T. Stokes
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Synaptic Transmission ◽  
Disulfonic Acid ◽  
Reactive Blue 2 ◽  
Neuronal Phenotype ◽  
Myenteric Neurons ◽  
P2 Purinoceptors ◽  
Gamma S

Fura 2 microfluorimetry was used to test the hypothesis that ATP acts at P1 and P2 purinoceptors to elevate cytosolic free Ca2+ concentrations [Ca2+]i) in calbindin-immunoreactive cultured myenteric neurons from adult guinea pig small intestine. Local "micro-puff" application of ATP or ATP(gamma)S caused an increase in [Ca2+]i in 99% of 200 multipolar neurons. The potency profile of agonists for the rise in [Ca2+]i was ATP(gamma)S = ATP >> ADP >> AMP, adenosine, 5'-(N-ethylcarboxamido)adenosine, and 2-chloro-N(6)-cyclopentyladenosine. Tetrodotoxin-sensitive synaptic transmission could contribute as much as 25% to the ATP response. The P1 antagonist 8-cyclopentyl-1,3-dipropylxanthine blocked 50% of the peakATP Ca2+ response. P2 antagonists blocked the ATP response: pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid > reactive blue 2 > suramin. Suramin enhanced the ATP response in 27.5% of neurons. Some neurons (<15%) displayed distinct multiphasic Ca2+ signatures. About 54% of ATP-responsive neurons expressed calbindin. The data support the following hypotheses: 1) two distinct P2 purinoceptors are linked to the rise in [Ca2+]i in myenteric neurons; 2) purinergic Ca2+ signaling is not restricted to one neuronal phenotype; and 3) intraneuronal Ca2+ is not involved in adenosinergic hyperpolarization in AH/type 2 neurons.

Immunochemical visualization of cyclic AMP in myenteric neurons of guinea-pig small intestine+

2001 ◽  
Vol 120 (5) ◽  
pp. A683-A683
Author(s):  
J GUZMAN ◽  
S SHARP ◽  
J YU ◽  
F MCMORRIS ◽  
A WIEMELT ◽  
...  
Keyword(s):  
Small Intestine ◽  
Cyclic Amp ◽  
Guinea Pig ◽  
Myenteric Neurons

Effects of PACAP on morphologically identified myenteric neurons in guinea pig small bowel

1993 ◽  
Vol 264 (3) ◽  
pp. G414-G421 ◽  
Author(s):  
F. L. Christofi ◽  
J. D. Wood
Keyword(s):  
Small Bowel ◽  
Adenylate Cyclase ◽  
Guinea Pig ◽  
Glial Cells ◽  
Input Resistance ◽  
Myenteric Neurons ◽  
Adenosine Receptor Agonist ◽  
Excitatory Responses

Intracellular microelectrodes were used to examine the actions of pituitary adenylate cyclase-activating peptide (PACAP) on morphologically identified myenteric neurons and glial cells of the guinea pig small bowel. PACAP-27 and PACAP-38 evoked excitatory responses in 96% of after hyperpolarizing (AH)/type 2 neurons. The half-maximal concentration for PACAP-27 was 1.5 nM. The responses consisted of membrane depolarization in association with increased input resistance, suppression of hyperpolarizing afterpotentials, and repetitive spike discharge. Forskolin mimicked the action of PACAP in all AH/type 2 neurons. PACAP excited 36% of S/type 1 neurons. Most of the AH/type 2 neurons had Dogiel II morphology, whereas the S/type 1 neurons were uniaxonal with morphology characteristics of Dogiel I or filamentous neurons. No glial cells responded to PACAP. A selective A1 adenosine receptor agonist blocked the excitatory action of PACAP, and this was reversed by a selective A1 antagonist. The results suggest that excitatory PACAP receptors and inhibitory adenosine A1 receptors are linked to adenylate cyclase in AH/type 2 myenteric neurons.

Patch-clamp recording in myenteric neurons of guinea pig small intestine

1992 ◽  
Vol 262 (6) ◽  
pp. G1074-G1078 ◽  
Author(s):  
L. V. Baidan ◽  
A. V. Zholos ◽  
M. F. Shuba ◽  
J. D. Wood
Keyword(s):  
Small Intestine ◽  
Patch Clamp ◽  
Guinea Pig ◽  
Calcium Currents ◽  
Delayed Rectifier ◽  
Patch Clamp Recording ◽  
Myenteric Neurons ◽  
Delayed Rectifier Current ◽  
Outward Currents ◽  
Current Clamp Mode

The results of our research established the feasibility of applying patch-clamp methods in the study of the cellular neurophysiology of myenteric neurons enzymatically dissociated from adult guinea pig small intestine. Recording in current-clamp mode revealed two populations of neurons. One population discharged repetitively during depolarizing current pulses and displayed anodal-break excitation reminiscent of S/type 1 myenteric neurons. In the second population, spike discharge was limited to one or two spikes at the onset of depolarizing pulses and was similar to the behavior of AH/type 2 neurons. Recording in voltage-clamp mode revealed a complex of overlapping inward and outward whole cell currents. Fast and slow components of inward current were interpreted as sodium and calcium currents, respectively. Outward currents were blocked by cesium and consisted of components with properties of delayed rectifier current and A-type potassium current.

An intracellular study of myenteric neurons in the mouse colon

1986 ◽  
Vol 55 (6) ◽  
pp. 1395-1406 ◽  
Author(s):  
K. Furukawa ◽  
G. S. Taylor ◽  
R. A. Bywater
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Nerve Stimulation ◽  
Circular Muscle ◽  
Input Resistance ◽  
Synaptic Activity ◽  
Myenteric Neurons ◽  
Mouse Colon ◽  
Long Latency ◽  
Wide Range

Intracellular recordings have been made in vitro from the myenteric neurons of the distal colon of normal littermates of the piebald-lethal mouse. Out of a total of 90 neurons, 82 were classified as S/type 1 cells and 8 as AH/type 2 cells. Seventy-eight out of 82 S cells showed spontaneous fast excitatory postsynaptic potentials (EPSPs) sensitive to d-tubocurarine (dTC, 280 microM), and 22 S cells showed spontaneous action potentials (APs). Six S cells and 1 AH cell showed spontaneous nonnicotinic slow depolarizations associated with an increase in the input resistance of the cells; during the spontaneous slow depolarization in the S cells there was an increase in the frequency of nicotinic fast EPSPs and APs. Three S cells showed spontaneously occurring regular oscillations of the membrane potential (approximately mV in amplitude and approximately 4/min). Transmural nerve stimulation produced fast EPSPs with a wide range of latencies (3 ms to 20 s) in S cells; the fast EPSPs were blocked by dTC (280 microM) or solutions containing low Ca2+ (0.25 mM) and high Mg2+ (12 mM) but not by atropine (ATR, 14 microM). Single or repetitive transmural stimulation produced slow EPSPs in 24 S cells and 3 AH cells; these were not blocked by dTC (280 microM) nor ATR (14 microM). During the slow EPSPs there was an increase in the input resistance of the cells. In those S cells that showed slow EPSPs there were many long-latency fast EPSPs; long-latency fast EPSPs were also observed in 11 other S cells that did not show a slow EPSP following repetitive transmural nerve stimulation. Long-latency fast EPSPs may be related to the firing of other neurons during their slow EPSPs. The myenteric neurons in the mouse colon have similar properties to the myenteric neurons in the guinea pig small intestine. However, the colonic myenteric neurons show more ongoing synaptic activity and more prolonged activity after nerve stimulation than myenteric neurons in the guinea pig small intestine. This activity may be due to regional differences, species differences, or preparation differences (in this study the myenteric plexus was adherent to the underlying circular muscle layer).

Excitatory actions of motilin on myenteric neurons of the guinea-pig small intestine

2005 ◽  
Vol 118 (1-2) ◽  
pp. 88-92 ◽  
Author(s):  
Yoshifumi Katayama ◽  
Kiyotoshi Ooishi ◽  
Keiji Hirai ◽  
Tomoo Homma ◽  
Yumi Noda
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Myenteric Neurons
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