The effects of several Ca2+ channel blockers were evaluated on inhibitory junction potential (IJP) evoked in rat colonic circular muscle by electrical field stimulation (EFS). Glass microelecrodes were used to record membrane potential of smooth muscle cells. IJPs were tetrodotoxin-sensitive (1 microM) and disappeared in Ca(2+)-free solution. L-type calcium channels blockers, such as nifedipine (1 microM) or verapamil (1 microM), did not affect IJPs. IJPs were significantly reduced by omega-conotoxin GVIA (300 nM), an N-type Ca2+ channel blocker. IJPs were resistant to omega-agatoxin IVA (50 nM), a P-type Ca2+ channel blocker, and omega-conotoxin MVIIC (1 microM), which blocks both N- and Q-type Ca2+ channels at micromolar concentrations. We conclude that the release of NANC neurotransmitter-mediating IJPs in the rat colon evoked by EFS involves N-type Ca2+ channels. The fact that omega-conotoxin GVIA does not abolish the IJPs suggests a putative role for L-, P- or Q-type Ca2+ channels.
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http://dx.doi.org/10.1016/0304-3940(96)12671-9 | DOI Listing |
BMC Complement Med Ther
December 2024
Department of Pediatrics, E-Da Hospital, I-Shou University, No. 1, Yi-Da Road, Yan-Chao District, Kaohsiung City, 82445, Taiwan, R.O.C..
J Physiol
September 2024
Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, USA.
The subiculum is a key region of the brain involved in the initiation of pathological activity in temporal lobe epilepsy, and local GABAergic inhibition is essential to prevent subicular-originated epileptiform discharges. Subicular pyramidal cells may be easily distinguished into two classes based on their different firing patterns. Here, we have compared the strength of the GABAa receptor-mediated inhibitory postsynaptic currents received by regular- vs.
View Article and Find Full Text PDFEur J Pharmacol
June 2024
Universitat Autònoma de Barcelona, Department of Cell Biology, Physiology and Immunology, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain. Electronic address:
Introduction: Hyoscine butylbromide (HBB) is one of the most used antispasmodics in clinical practice. Recent translational consensus has demonstrated a similarity between human colonic motor patterns studied ex vivo and in vivo, suggesting ex vivo can predict in vivo results. It is unclear whether the mechanism of action of antispasmodics can predict different use in clinical practice.
View Article and Find Full Text PDFEur J Pharmacol
January 2024
School of Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang Dist, New Taipei City, 24205, Taiwan; Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, 33303, Taiwan. Electronic address:
The present study evaluated the effect of ursolic acid, a natural pentacyclic triterpenoid, on glutamate release in rat cortical nerve terminals (synaptosomes) and its neuroprotection in a kainic acid-induced excitotoxicity rat model. In cortical synaptosomes, ursolic acid produced a concentration-dependent inhibition of evoked glutamate release with a half-maximum inhibition of release value of 9.5 μM, and calcium-free medium and the P/Q -type Ca channel blocker, ω-agatoxin IVA, but not ω-conotoxin GVIA, an N-type Ca channel blocker, prevented the ursoloic acid effect.
View Article and Find Full Text PDFMol Neurobiol
April 2024
Department of Biophysics, Meram Faculty of Medicine, University of Konya-NE, Konya, Turkey.
High-voltage-gated calcium channels have pivot role in the cellular and molecular mechanisms of various neurological disorders, including epilepsy. Similar to other calcium channels, P/Q-type calcium channels (Ca2.1) are also responsible for vesicle release at synaptic terminals.
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