![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
T Takahashi, Y Tsunoda, Y Lu, J Wiley and C Owyang
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor.
Entry of extracellular calcium (Ca++) via voltage-gated Ca++ channels is essential for neurotransmitter release. In this study, we examined whether nicotinic receptor-stimulated release of acetylcholine (ACh) and somatostatin (S14) are coupled to calcium influx via distinct calcium channel subtypes in the myenteric plexus. Isolated ganglia from the guinea pig ileal myenteric plexus were prepared and placed in perfusion chambers under standard conditions. The ganglionic agonist dimethylphenylpiperazinium (DMPP, 10(-6) to 10(-3) M) stimulated the release of [3H]ACh in a concentration-dependent manner. This release was blocked by hexamethonium or Ca(++)-free medium containing 1 mM EGTA and was antagonized by omega-conotoxin, a preferential N calcium channel blocker, but was not affected by nifedipine (L channel antagonist) or nickel (T calcium channel antagonist). DMPP-evoked release of somatostatin was also antagonized by omega-conotoxin, but was not affected by nifedipine or nickel. These observations indicate that neurosecretion of ACh and S14 evoked by DMPP is mediated by calcium entry via voltage-sensitive N-type Ca++ channels. To provide additional evidence that nicotinic receptor stimulation is associated with Ca++ entry via the N-type Ca++ channels, we examined the intracellular calcium [Ca++]i concentration of the myenteric plexus neurons using fura-2 microspectrofluorometry. Basal [Ca++]i of single ileal myenteric neurons was 65 +/- 5 nM. Perfusion with DMPP (10(-6) to 10(-3) M) caused a rapid, transient elevation in [Ca++]i which was abolished by Ca(++)-free medium containing 1 mM EGTA.(ABSTRACT TRUNCATED AT 250 WORDS)
This article has been cited by other articles:
|
|
 |
|
  B. Lendvai and E. S. Vizi Nonsynaptic Chemical Transmission Through Nicotinic Acetylcholine Receptors Physiol Rev, April 1, 2008; 88(2): 333 - 349. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. E. Wunderlich, B. J. Needleman, Z. Chen, J. G. Yu, Y. Wang, I. Grants, D. J. Mikami, W. S. Melvin, H. J. Cooke, and F. L. Christofi Dual purinergic synaptic transmission in the human enteric nervous system Am J Physiol Gastrointest Liver Physiol, February 1, 2008; 294(2): G554 - G566. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
X. Bian, X. Zhou, and J. J. Galligan R-type calcium channels in myenteric neurons of guinea pig small intestine Am J Physiol Gastrointest Liver Physiol, July 1, 2004; 287(1): G134 - G142. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Bisschops, P. Vanden Berghe, E. Bellon, J. Janssens, and J. Tack Electrical stimulation reveals complex neuronal input and activation patterns in single myenteric guinea pig ganglia Am J Physiol Gastrointest Liver Physiol, June 1, 2003; 284(6): G1084 - G1092. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. A. Schneider and J. J. Galligan Presynaptic nicotinic acetylcholine receptors in the myenteric plexus of guinea pig intestine Am J Physiol Gastrointest Liver Physiol, September 1, 2000; 279(3): G528 - G535. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Vanden Berghe, J. Tack, A. Andrioli, L. Missiaen, and J. Janssens Receptor-induced Ca2+ signaling in cultured myenteric neurons Am J Physiol Gastrointest Liver Physiol, June 1, 2000; 278(6): G905 - G914. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Akiyama and T. Yamazaki Adrenergic inhibition of endogenous acetylcholine release on postganglionic cardiac vagal nerve terminals Cardiovasc Res, June 1, 2000; 46(3): 531 - 538. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Kojima, Y. Tsunoda, and C. Owyang Adenosine 3',5'-Cyclic Monophosphate-Stimulated Ca++ Efflux and Acetylcholine Release in Ileal Myenteric Plexus Are Mediated by N-Type Ca++ Channels: Inhibition by the Kappa Opioid Receptor Agonist J. Pharmacol. Exp. Ther., July 1, 1997; 282(1): 403 - 409. [Abstract] [Full Text]
|
|
 |
 |
 |
|
 |
 |
 |
