Biomaterial Database

Quinidine blockade of the carbachol-activated nonselective cationic current in guinea-pig gastric myocytes. 1995

S J Kim, and S C Ahn, and I So, and K W Kim

Department of Physiology & Biophysics, Seoul National University College of Medicine, Korea.

1. In guinea-pig gastric myocytes isolated from the antral circular layer, stimulation of muscarinic receptors by carbachol (CCh) induces a cationic current (ICCh) which is known as the main mechanism of depolarization induced by muscarinic stimulation. 2. We tested the effects of a number of ion channel blockers on ICCh and focused upon quinidine which was a highly potent blocker. Externally applied quinidine suppressed ICCh (IC50 = 0.25 microM) in a reversible and voltage-dependent manner. Applied internally, quinidine was about 100 times less potent than when applied externally. Persistent activation of G-protein by GTP gamma S also induced a cationic current similar to ICCh and this current was also blocked by quinidine. 4-Aminopyridine and tetraethylammonium also suppressed ICCh in a dose-dependent manner (IC50 = 3.3 mM and 4.1 mM, respectively). 3. Pretreatment with quinidine (2 microM) selectively blocked the acetylcholine (ACh)-induced depolarization which was recorded in the multicellular tissues by a conventional intracellular microelectrode technique. 4. Voltage-dependent K-currents were also suppressed by quinidine but in a higher concentration range (IC50 = 3 microM). Quinidine, 10 microM, decreased the amplitude of the voltage-dependent Ca current to only a small extent (15% decrease at 0 mV). Quinidine, 2 microM, also suppressed only a minute proportion of the Ca-activated K current (11.1% decrease at 45 mV). 5. From these experiments, it is concluded that some organic agents known as K channel blockers are able to block the CCh-activated cation channel in a non-specific manner and among them, quinidine can be used as an effective blocker for ICCh in guinea-pig gastric myocytes.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008839	Microelectrodes	Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)	Electrodes, Miniaturized,Electrode, Miniaturized,Microelectrode,Miniaturized Electrode,Miniaturized Electrodes
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D011802	Quinidine	An optical isomer of quinine, extracted from the bark of the CHINCHONA tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular ACTION POTENTIALS, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission.	Adaquin,Apo-Quinidine,Chinidin,Quincardine,Quinidex,Quinidine Sulfate,Quinora,Apo Quinidine,Sulfate, Quinidine
D011976	Receptors, Muscarinic	One of the two major classes of cholinergic receptors. Muscarinic receptors were originally defined by their preference for MUSCARINE over NICOTINE. There are several subtypes (usually M1, M2, M3....) that are characterized by their cellular actions, pharmacology, and molecular biology.	Muscarinic Acetylcholine Receptors,Muscarinic Receptors,Muscarinic Acetylcholine Receptor,Muscarinic Receptor,Acetylcholine Receptor, Muscarinic,Acetylcholine Receptors, Muscarinic,Receptor, Muscarinic,Receptor, Muscarinic Acetylcholine,Receptors, Muscarinic Acetylcholine
D002217	Carbachol	A slowly hydrolyzed CHOLINERGIC AGONIST that acts at both MUSCARINIC RECEPTORS and NICOTINIC RECEPTORS.	Carbamylcholine,Carbacholine,Carbamann,Carbamoylcholine,Carbastat,Carbocholine,Carboptic,Doryl,Isopto Carbachol,Jestryl,Miostat,Carbachol, Isopto
D002412	Cations	Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.	Cation
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D005260	Female		Females