Stimulation of adenosine A1 and A2A receptors by AMP in the submucosal plexus of guinea pig small intestine

2007 ◽  
Vol 292 (2) ◽  
pp. G492-G500 ◽  
Author(s):  
Na Gao ◽  
Hong-Zhen Hu ◽  
Sumei Liu ◽  
Chuanyun Gao ◽  
Yun Xia ◽  
...  
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Receptor Antagonist ◽  
Pyridoxal Phosphate ◽  
Disulfonic Acid ◽  
Receptor Subtype ◽  
Excitatory Postsynaptic Potentials ◽  
Submucosal Plexus ◽  
Postsynaptic Potentials ◽  
Stimulation Of

Actions of adenosine 5′-monophosphate (AMP) on electrical and synaptic behavior of submucosal neurons in guinea pig small intestine were studied with “sharp” intracellular microelectrodes. Application of AMP (0.3–100 μM) evoked slowly activating depolarizing responses associated with increased excitability in 80.5% of the neurons. The responses were concentration dependent with an EC50 of 3.5 ± 0.5 μM. They were abolished by the adenosine A2A receptor antagonist ZM-241385 but not by pyridoxal-phosphate-6-azophenyl-2,4-disulfonic acid, trinitrophenyl-ATP, 8-cyclopentyl-1,3-dimethylxanthine, suramin, or MRS-12201220. The AMP-evoked responses were insensitive to AACOCF3 or ryanodine. They were reduced significantly by 1) U-73122, which is a phospholipase C inhibitor; 2) cyclopiazonic acid, which blocks the Ca2+ pump in intraneuronal membranes; and 3) 2-aminoethoxy-diphenylborane, which is an inositol ( 1 , 4 , 5 )-trisphosphate receptor antagonist. Inhibitors of PKC or calmodulin-dependent protein kinase also suppressed the AMP-evoked excitatory responses. Exposure to AMP suppressed fast nicotinic ionotropic postsynaptic potentials, slow metabotropic excitatory postsynaptic potentials, and slow noradrenergic inhibitory postsynaptic potentials in the submucosal plexus. Inhibition of each form of synaptic transmission reflected action at presynaptic inhibitory adenosine A1 receptors. Slow excitatory postsynaptic potentials, which were mediated by the release of ATP and stimulation of P2Y1 purinergic receptors in the submucosal plexus, were not suppressed by AMP. The results suggest an excitatory action of AMP at adenosine A2A receptors on neuronal cell bodies and presynaptic inhibitory actions mediated by adenosine A1 receptors for most forms of neurotransmission in the submucosal plexus, with the exception of slow excitatory purinergic transmission mediated by the P2Y1 receptor subtype.

Organization of intrinsic cholinergic neurons projecting within submucosal plexus of guinea pig ileum

1998 ◽  
Vol 275 (3) ◽  
pp. G490-G497 ◽  
Author(s):  
B. A. Moore ◽  
S. Vanner
Keyword(s):  
Guinea Pig ◽  
Pressure Pulse ◽  
Cholinergic Neurons ◽  
Excitatory Postsynaptic Potentials ◽  
Submucosal Plexus ◽  
Guinea Pig Ileum ◽  
Postsynaptic Potentials ◽  
Ics 205 930 ◽  
Stimulation Of

Electrophysiological techniques were employed to examine the organization of the projections of submucosal neurons in the submucosal plexus of guinea pig ileum. These neurons were activated by focal pressure-pulse application of 5-hydroxytryptamine (5-HT) to single ganglia in submucosal preparations in vitro, and resulting fast excitatory postsynaptic potentials (EPSPs) were recorded intracellularly in S-type neurons. 5-HT-evoked fast EPSPs were blocked by TTX, hexamethonium, and ICS-205-930 (tropisetron). 5-HT was applied either directly to the ganglion containing the neuron recorded intracellularly or to adjacent ganglia positioned at increasing distances on either side of the impaled cell in circumferential or longitudinal orientations. All S-type neurons recorded in this study ( n = 103) received nicotinic fast EPSPs from cholinergic neurons when 5-HT was applied directly to the ganglion containing the impaled neuron. Stimulation of adjacent ganglia also evoked nicotinic fast EPSPs, but the number of neurons that received this input decreased as the distance between the stimulus and the impaled cell increased. Maximal projections were 3 mm in the circumferential and orad-to-aborad orientations. There were no significant projections in the aborad-to-orad direction. These findings suggest that S-type neurons in the submucosal plexus are innervated by intrinsic cholinergic neurons that project over relatively short distances and have a distinct orad-to-aborad polarity.

Excitatory postsynaptic potentials evoked by ventral root stimulation in neonate rat motoneurons in vitro

1991 ◽  
Vol 65 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Z. G. Jiang ◽  
E. Shen ◽  
M. Y. Wang ◽  
N. J. Dun
Keyword(s):  
Receptor Antagonist ◽  
Response Latency ◽  
Ventral Root ◽  
Synaptic Delay ◽  
Excitatory Postsynaptic Potentials ◽  
Related Substance ◽  
Postsynaptic Potentials ◽  
Axon Collaterals ◽  
Hyperpolarizing Response ◽  
Stimulation Of

1. Intracellular recordings were made from antidromically identified motoneurons in transverse (500 microns) lumbar spinal cord slices of neonatal (12-20 day) rats. 2. Electrical stimulation of ventral rootlets evoked, with or without an antidromic spike or initial segment potential, a depolarizing response (latency, 1-4.2 ms), a hyperpolarizing response (latency, 1.5-3.5 ms), or a combination of two preceding responses in 38, 6, and 8% of motoneurons investigated. 3. The hyperpolarizing response was reversibly eliminated by low Ca2+ (0.25 mM), d-tubocurarine (d-Tc; 10 microM) or strychnine (1 microM), suggesting that this response represents an inhibitory post-synaptic potential (IPSP) mediated by glycine or a related substance release from inhibitory interneurons subsequent to their activation by axon collaterals in a manner analogous to the Renshaw cell circuitry described for the cat motoneurons. 4. The depolarizing responses were excitatory postsynaptic potentials (EPSPs), because they could be graded by varying the stimulus intensity and were reversibly abolished in low Ca2+ solution. 5. Membrane hyperpolarization increased the amplitude of EPSPs, and the mean extrapolated reversal potential was -4 mV. 6. EPSPs were augmented, rather than diminished, by dihydro-beta-erythroidine (1 microM) or d-Tc, arguing against a role of recurrent motor axon collaterals in initiating the responses. 7. The conduction velocity of the fibers initiating the EPSPs ranged from 0.35 to 0.96 m/s, indicating that these fibers were unmyelinated. Furthermore, the EPSP exhibited a constant delay when the stimulus frequency was varied from 1 to 5 Hz, and the synaptic delay estimated by extrapolation was less than 1 ms, suggesting that it was a monosynaptic event. 8. After complete separation of the ventral and dorsal horns by a knife cut, stimulation of ventral rootlets could still evoke an EPSP in motoneurons. 9. Superfusion of the slices with the nonselective glutamate receptor antagonist kynurenic acid (0.2-1 mM) or the selective quisqualate/kainate receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) (0.5-1 microM) reversibly diminished the EPSPs. 10. EPSPs evoked by stimulation of dorsal and ventral rootlets exhibited different latency and waveform in the same motoneurons. 11. The results provide evidence that activation of ventral root afferents evoked an EPSP mediated by glutamate or a related substance in a population of motoneurons. Furthermore, the afferent pathway mediating the EPSP appears to be monosynaptic and confined to the ventral horn.

scholarly journals ATP induces guinea pig gallbladder smooth muscle excitability via the P2Y4 receptor and COX-1 activity

2008 ◽  
Vol 294 (6) ◽  
pp. G1362-G1368 ◽  
Author(s):  
Aaron C. Bartoo ◽  
Mark T. Nelson ◽  
Gary M. Mawe
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Pyridoxal Phosphate ◽  
Membrane Depolarization ◽  
Disulfonic Acid ◽  
Receptor Subtype ◽  
Excitatory Response ◽  
Prostanoid Production ◽  
Similar Dose ◽  
Cox 1

The purpose of this study was to elucidate the mechanisms by which ATP increases guinea pig gallbladder smooth muscle (GBSM) excitability. We evaluated changes in membrane potential and action potential (AP) frequency in GBSM by use of intracellular recording. Application of ATP (100 μM) caused membrane depolarization and a significant increase in AP frequency that were not sensitive to block by tetrodotoxin (0.5 μM). The nonselective P2 antagonist, suramin (100 μM), blocked the excitatory response, resulting in decreased AP frequency in the presence of ATP. The excitatory response to ATP was not altered by pyridoxal-phosphate-6-azophenyl-2,4-disulfonic acid (30 μM), a nonselective P2X antagonist. UTP also caused membrane depolarization and increased AP frequency, with a similar dose-response relationship as ATP. RT-PCR demonstrated that the P2Y4, but not P2Y2, receptor subtype is expressed in guinea pig gallbladder muscularis. ATP induced excitation was blocked by indomethacin (10 μM) and the cyclooxygenase (COX)-1 inhibitor SC-560 (300 nM), but not the COX-2 inhibitor nimesulide (500 nM). These data suggest that ATP stimulates P2Y4 receptors within the gallbladder muscularis and, in turn, stimulate prostanoid production via COX-1 leading to increased excitability of GBSM.

Connexions Between a Movement-Detecting Visual Interneurone and Flight Motoneurones of a Locust

1980 ◽  
Vol 86 (1) ◽  
pp. 87-97
Author(s):  
PETER SIMMONS
Keyword(s):  
Movement Detector ◽  
Excitatory Postsynaptic Potentials ◽  
Schistocerca Americana ◽  
Postsynaptic Potentials ◽  
Contralateral Movement ◽  
Contralateral Eye ◽  
Stimulation Of

Both of the descending contralateral movement detector (DCMD) neurones of Schistocerca americana gregaria, which respond to stimulation of the contralateral eye or to loud noises, mediate excitatory postsynaptic potentials in most ipsilateral flight motoneurones.

Some species differences in the intrinsic factor stimulation of B12 uptake by small intestine in vitro

1959 ◽  
Vol 197 (4) ◽  
pp. 926-928 ◽  
Author(s):  
T. Hastings Wilson ◽  
Elliott W. Strauss
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Species Differences ◽  
Intrinsic Factor ◽  
Vitamin B ◽  
Guinea Pig Ileum ◽  
Rat Intestine ◽  
Intrinsic Factors ◽  
Stimulation Of

Sacs of everted small intestine from a variety of animals were incubated in bicarbonate-saline containing vitamin B12 with and without intrinsic factor (IF). B12 uptake by rat intestine was stimulated only by its own intrinsic factor. Guinea pig ileum responded to all intrinsic factors tested (guinea pig, rat, hog, hamster, human being and rabbit). The intestines of hamster and rabbit were intermediate in specificity, responding to some, but not all, of the IF preparations. Species differences occur in both the intestine and intrinsic factor preparations. The guinea pig ileum was suggested as a possible assay for both hog and human IF.

scholarly journals ATP is involved in myocardial and vascular effects of exogenous bradykinin in ejecting guinea pig heart

1999 ◽  
Vol 277 (2) ◽  
pp. H818-H825 ◽  
Author(s):  
Peter B. Anning ◽  
Bernard D. Prendergast ◽  
Philip A. MacCarthy ◽  
Ajay M. Shah ◽  
Derek C. Buss ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Guinea Pig ◽  
Coronary Flow ◽  
Pyridoxal Phosphate ◽  
Left Ventricular ◽  
Luciferase Assay ◽  
Disulfonic Acid ◽  
Vascular Effects ◽  
Guinea Pig Heart ◽  
Nitric Oxide Release

It has recently been reported that bradykinin induces selective left ventricular (LV) relaxation in isolated guinea pig hearts via the release of nitric oxide. Exogenous bradykinin also induces vasodilation, which is only partly due to nitric oxide release. In the present study we investigated the role of adenyl purines on these bradykinin-induced effects. Isolated ejecting guinea pig hearts were studied. LV pressure was monitored by a 2-Fr micromanometer-tipped catheter. ATP concentrations were measured using a luciferin-luciferase assay. Bradykinin (1 and 100 nM) caused a progressive acceleration of LV relaxation together with a transient increase in coronary flow. These effects were inhibited by the nonselective P2 purinoceptor antagonist suramin (1 μM, n = 6) but were unaffected by the selective P2x purinoceptor antagonist pyridoxal phosphate 6-azophenyl-2′,4′-disulfonic acid (1 μM, n = 6). These myocardial and vascular effects of bradykinin were associated with increased ATP levels in coronary effluent. These data suggest that the selective enhancement of LV relaxation and rise in coronary flow induced by exogenous bradykinin involve endogenous ATP and the subsequent stimulation of P2 purinoceptors.

Excitatory transmission in the basolateral amygdala

1991 ◽  
Vol 66 (3) ◽  
pp. 986-998 ◽  
Author(s):  
D. G. Rainnie ◽  
E. K. Asprodini ◽  
P. Shinnick-Gallagher
Keyword(s):  
Nmda Receptor ◽  
Receptor Antagonist ◽  
Nmda Antagonist ◽  
Receptor Activation ◽  
Nmda Receptor Antagonist ◽  
Current Injection ◽  
Membrane Hyperpolarization ◽  
Postsynaptic Potentials ◽  
The Mean ◽  
Stimulation Of

1. Intracellular current-clamp recordings obtained from neurons of the basolateral nucleus of the amygdala (BLA) were used to characterize postsynaptic potentials elicited through stimulation of the stria terminalis (ST) or the lateral amygdala (LA). The contribution of glutamatergic receptor subtypes to excitatory postsynaptic potentials (EPSPs) were analyzed by the use of the non N-methyl-D-aspartate (non-NMDA) antagonist, 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX), and the NMDA antagonist, (DL)-2-amino-5-phosphonovaleric acid (APV). 2. Basic membrane properties of BLA neurons determined from membrane responses to transient current injection showed that at the mean resting membrane potential (RMP; -67.2 mV) the input resistance (RN) and time constant for membrane charging (tau) were near maximal, and that both values were reduced with membrane hyperpolarization, suggesting an intrinsic regulation of synaptic efficacy. 3. Responses to stimulation of the ST or LA consisted of an EPSP followed by either a fast inhibitory postsynaptic potential (f-IPSP) only, or by a fast- and subsequent slow-IPSP (s-IPSP). The EPSP was graded in nature, increasing in amplitude with increased stimulus intensity, and with membrane hyperpolarization after DC current injection. Spontaneous EPSPs were also observed either as discrete events or as EPSP/IPSP waveforms. 4. In physiological Mg2+ concentrations (1.2 mM), at the mean RMP, the EPSP consisted of dual, fast and slow, glutamatergic components. The fast-EPSP (f-EPSP) possessed characteristics of kainate/quisqualate receptor activation, namely, the EPSP increased in amplitude with membrane hyperpolarization, was insensitive to the NMDA receptor antagonist, APV (50 microM), and was blocked by the non-NMDA receptor antagonist, CNQX (10 microM). In contrast, the slow-EPSP (s-EPSP) decreased in amplitude with membrane hyperpolarization, was insensitive to CNQX (10 microM), and was blocked by APV (50 microM), indicating mediation by NMDA receptor activation. 5. In the presence of CNQX (10 microM), ST stimulation evoked an APV-sensitive s-EPSP. In contrast, LA stimulation evoked a f-IPSP, which when blocked by subsequent addition of bicuculline methiodide (BMI; 30 microM) revealed a temporally overlapping APV-sensitive s-EPSP. These data suggest that EPSP amplitude and duration are determined, in part, by the shunting of membrane conductance caused by a concomitant IPSP. 6. Superfusion of either CNQX or APV in BLA neurons caused membrane hyperpolarization and blockade of spontaneous EPSPs and IPSPs, suggesting that these compounds may act to block tonic excitatory amino acid (EAA) release within the nucleus, and that a degree of feed-forward inhibition occurs within the nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Innervation of enteric mast cells by primary spinal afferents in guinea pig and human small intestine

2014 ◽  
Vol 307 (7) ◽  
pp. G719-G731 ◽  
Author(s):  
Guo-Du Wang ◽  
Xi-Yu Wang ◽  
Sumei Liu ◽  
Meihua Qu ◽  
Yun Xia ◽  
...  
Keyword(s):  
Nervous System ◽  
Mast Cell ◽  
Small Intestine ◽  
Electrical Stimulation ◽  
Mast Cells ◽  
Guinea Pig ◽  
Mast Cell Protease ◽  
Human Small Intestine ◽  
Neurokinin 1 ◽  
Stimulation Of

Mast cells express the substance P (SP) neurokinin 1 receptor and the calcitonin gene-related peptide (CGRP) receptor in guinea pig and human small intestine. Enzyme-linked immunoassay showed that activation of intramural afferents by antidromic electrical stimulation or by capsaicin released SP and CGRP from human and guinea pig intestinal segments. Electrical stimulation of the afferents evoked slow excitatory postsynaptic potentials (EPSPs) in the enteric nervous system. The slow EPSPs were mediated by tachykinin neurokinin 1 and CGRP receptors. Capsaicin evoked slow EPSP-like responses that were suppressed by antagonists for protease-activated receptor 2. Afferent stimulation evoked slow EPSP-like excitation that was suppressed by mast cell-stabilizing drugs. Histamine and mast cell protease II were released by 1) exposure to SP or CGRP, 2) capsaicin, 3) compound 48/80, 4) elevation of mast cell Ca2+ by ionophore A23187, and 5) antidromic electrical stimulation of afferents. The mast cell stabilizers cromolyn and doxantrazole suppressed release of protease II and histamine when evoked by SP, CGRP, capsaicin, A23187, electrical stimulation of afferents, or compound 48/80. Neural blockade by tetrodotoxin prevented mast cell protease II release in response to antidromic electrical stimulation of mesenteric afferents. The results support a hypothesis that afferent innervation of enteric mast cells releases histamine and mast cell protease II, both of which are known to act in a diffuse paracrine manner to influence the behavior of enteric nervous system neurons and to elevate the sensitivity of spinal afferent terminals.

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