scholarly journals Resolution and concordance in dissecting the compound inhibitory junction potential

2012 ◽  
Vol 590 (8) ◽  
pp. 1777-1778 ◽  
Author(s):  
Brian F. King
Keyword(s):  
Inhibitory Junction Potential ◽  
Junction Potential

Effect of exogenous ATP on canine jejunal smooth muscle

2000 ◽  
Vol 278 (5) ◽  
pp. G725-G733 ◽  
Author(s):  
L. Xue ◽  
G. Farrugia ◽  
J. H. Szurszewski
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Pyridoxal Phosphate ◽  
Electrical Field Stimulation ◽  
Muscle Cells ◽  
Disulfonic Acid ◽  
Reactive Blue 2 ◽  
Circular Smooth Muscle ◽  
Inhibitory Junction Potential ◽  
Junction Potential

Intracellular recordings were made from the circular smooth muscle cells of the canine jejunum to study the effect of exogenous ATP and to compare the ATP response to the nonadrenergic, noncholinergic (NANC) inhibitory junction potential (IJP) evoked by electrical field stimulation (EFS). Under NANC conditions, exogenous ATP evoked a transient hyperpolarization (6.5 ± 0.6 mV) and EFS evoked a NANC IJP (17 ± 0.4 mV). ω-Conotoxin GVIA (100 nM) and a low-Ca2+, high-Mg2+ solution abolished the NANC IJP but had no effect on the ATP-evoked hyperpolarization. The ATP-evoked hyperpolarization and the NANC IJP were abolished by apamin (1 μM) and N G-nitro-l-arginine (100 μM). Oxyhemoglobin (5 μM) partially (38.8 ± 5.5%) reduced the amplitude of the NANC IJP but had no effect on the ATP-evoked hyperpolarization. Neither the NANC IJP nor the ATP-evoked hyperpolarization was affected by P2 receptor antagonists or agonists, including suramin, reactive blue 2, 1-( N, O-bis-[5-isoquinolinesulfonyl]- N-methyl-l-tyrosyl)-4-phenylpiperazine, pyridoxal phosphate-6-azophenyl-2′,4′-disulfonic acid, α,β-methylene ATP, 2-methylthioadenosine 5′-triphosphate tetrasodium salt, and adenosine 5′- O-2-thiodiphosphate. The data suggest that ATP evoked an apamin-sensitive hyperpolarization in circular smooth muscle cells of the canine jejunum via local production of NO in a postsynaptic target cell.

Electrical responses of gastric smooth muscles in streptozotocin-induced diabetic rats

1997 ◽  
Vol 272 (1) ◽  
pp. G77-G83 ◽  
Author(s):  
L. Xue ◽  
H. Suzuki
Keyword(s):  
Smooth Muscles ◽  
Diabetic Rats ◽  
Maximum Activity ◽  
Resting Membrane Potential ◽  
Free Solution ◽  
Inhibitory Junction Potential ◽  
Myogenic Activity ◽  
Microelectrode Techniques ◽  
Junction Potential ◽  
Electrical Responses

Electrical responses of gastric smooth muscles produced by transmural nerve stimulation, acetylcholine, norepinephrine, or K-free solution were investigated in streptozotocin-induced diabetic rats, using intracellular microelectrode techniques. In muscles from diabetic rats, 1) the resting membrane potential remained unchanged, 2) slow waves disappeared or were markedly reduced in amplitude, 3) the excitatory junction potential was absent, and in most cases only an inhibitory junction potential of reduced amplitude was elicited, 4) the amplitude of the hyperpolarization generated after superfusion with K-free solution was reduced, 5) the sensitivity of the acetylcholine-induced membrane depolarization was increased, and 6) the norepinephrine-induced hyperpolarization was reduced because of functional loss of alpha- and beta-adrenoceptors. Thus diabetes mellitus caused functional impairment of neuromuscular transmission, reduced the maximum activity of the electrogenic pump, increased the sensitivity of muscarinic receptors, reduced the sensitivity of adrenoceptors, and reduced the myogenic activity in gastric smooth muscles. These alterations in the properties of smooth muscle may be involved in the diabetes-induced gastroparesis.

scholarly journals Burnstock and the legacy of the inhibitory junction potential and P2Y1 receptors

2020 ◽  
Author(s):  
Brian F. King
Keyword(s):  
Electromechanical Coupling ◽  
Subsequent Development ◽  
P2y Receptors ◽  
Purinergic Signalling ◽  
P2x7 Receptors ◽  
Receptor Field ◽  
Surface Receptors ◽  
Inhibitory Junction Potential ◽  
Synaptic Event ◽  
Junction Potential

AbstractThe synaptic event called the inhibitory junction potential (IJP) was arguably one of the more important discoveries made by Burnstock and arguably one of his finer legacies. The discovery of the IJP fundamentally changed how electromechanical coupling was visualised in gastrointestinal smooth muscle. Its discovery also set in motion the search for novel inhibitory neurotransmitters in the enteric nervous system, eventually leading to proposal that ATP or a related nucleotide was a major inhibitory transmitter. The subsequent development of purinergic signalling gave impetus to expanding the classification of surface receptors for extracellular ATP, not only in the GI tract but beyond, and then led to successive phases of medicinal chemistry as the P2 receptor field developed. Ultimately, the discovery of the IJP led to the successful cloning of the first P2Y receptor (chick P2Y1) and expansion of mammalian ATP receptors into two classes: metabotropic P2Y receptors (encompassing P2Y1, P2Y2, P2Y4, P2Y6, P2Y11–14 receptors) and ionotropic P2X receptors (encompassing homomeric P2X1–P2X7 receptors). Here, the causal relationship between the IJP and P2Y1 is explored, setting out the milestones reached and achievements made by Burnstock and his colleagues.

Suramin and the inhibitory junction potential in taenia caeci of the guinea-pig

1989 ◽  
Vol 173 (2-3) ◽  
pp. 207-209 ◽  
Author(s):  
Adriaan Den Hertog ◽  
Jan Van den Akker ◽  
Adriaan Nelemans
Keyword(s):  
Guinea Pig ◽  
Inhibitory Junction Potential ◽  
Junction Potential

Effects of γ-Aminobutyric Acid and Picrotoxin on the Permeability of the Longitudinal Muscle of the Earthworm to Various Anions

1969 ◽  
Vol 51 (2) ◽  
pp. 363-375
Author(s):  
Y. ITO ◽  
H. KURIYAMA ◽  
N. TASHIRO
Keyword(s):  
Membrane Potential ◽  
Response Curve ◽  
Longitudinal Muscle ◽  
Chloride Concentration ◽  
Reversal Potential ◽  
Input Resistance ◽  
Ringer Solution ◽  
Aminobutyric Acid ◽  
Inhibitory Junction Potential ◽  
Junction Potential

The effects of GABA and picrotoxin on the input resistance of the muscle of the earthworm, Pheretima communissima in Ringer solution and in solutions containing various foreign anions were observed. 1. Substitution of Cl- by I- and Br- reduced the input resistance and hyperpolarized the membrane. Although anions larger than chloride in hydrated size increased the input resistance, no change of the membrane potential was observed. 2. GABA reduced the input resistance of the membrane and picrotoxin increased it in Ringer solution. The dose-response curve for the changes of the input resistance under various concentrations of GABA shifted parallel-wise under treatment with picrotoxin. 3. In the presence of foreign anions which had larger hydration size than Br-, GABA reduced the input resistance. Picrotoxin did not, however, increase the input resistance when the solutions contained anions of smaller hydration size than ClO4-. 4. Reversal potential levels for the miniature inhibitory junction potential in various concentrations of chloride were measured. The change of the reversal potential levels produced by a tenfold change of chloride concentration was 25 mV.

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