Biomaterial Database

Beta-adrenoceptor-mediated hyperpolarization in lymphatic smooth muscle of guinea pig mesentery. 1996

P Y Von der Weid, and D F Van Helden

Neuroscience Group, Discipline of Human Physiology, Faculty of Medicine and Health Sciences, University of Newcastle, Callahan NSW, Australia.

Intracellular microelectrode recordings were performed to investigate the consequences of beta-adrenoceptor activation in smooth muscle of guinea pig mesenteric lymphatic vessels. Isoproterenol (Iso) hyperpolarized the membrane with an associated increase in membrane conductance and decreased the amplitude of spontaneous transient depolarizations. Iso effects were mimicked by forskolin (FSK), 3-isobutyl-1-methylxanthine, and two adenosine 3',5'-cyclic monophosphate (cAMP) derivatives. Iso- and FSK-induced hyperpolarizations were inhibited by H89, an inhibitor of cAMP-dependent protein kinase A, increased in K+-free solution, but were not affected by ouabain or by the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine. They were partially inhibited by 20 mM tetraethylammonium (approximately 40%) or by 2.5 mM 4-aminopyridine (approximately 55%). The-Iso-induced hyperpolarization was partially inhibited by iberiotoxin (20 nM) and charybdotoxin (40 nM), whereas the FSK-induced hyperpolarization was less affected. In cells where the Iso-induced hyperpolarization was decreased by 40 microM 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, acetoxymethyl ester form, the FSK-induced hyperpolarization was little changed. Our results indicate that in guinea pig mesenteric lymphatic vessels, beta-adrenoceptor stimulation activates a protein kinase A-dependent K+ conductance, involving more than one channel type.

UI	MeSH Term	Description	Entries
D007546	Isoquinolines	A group of compounds with the heterocyclic ring structure of benzo(c)pyridine. The ring structure is characteristic of the group of opium alkaloids such as papaverine. (From Stedman, 25th ed)
D008208	Lymphatic System	A system of organs and tissues that process and transport immune cells and LYMPH.	Lymphatic Systems
D008297	Male		Males
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D008643	Mesentery	A layer of the peritoneum which attaches the abdominal viscera to the ABDOMINAL WALL and conveys their blood vessels and nerves.	Mesenteries
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
D011943	Receptors, Adrenergic, beta	One of two major pharmacologically defined classes of adrenergic receptors. The beta adrenergic receptors play an important role in regulating CARDIAC MUSCLE contraction, SMOOTH MUSCLE relaxation, and GLYCOGENOLYSIS.	Adrenergic beta-Receptor,Adrenergic beta-Receptors,Receptors, beta-Adrenergic,beta Adrenergic Receptor,beta-Adrenergic Receptor,beta-Adrenergic Receptors,Receptor, Adrenergic, beta,Adrenergic Receptor, beta,Adrenergic beta Receptor,Adrenergic beta Receptors,Receptor, beta Adrenergic,Receptor, beta-Adrenergic,Receptors, beta Adrenergic,beta Adrenergic Receptors,beta-Receptor, Adrenergic,beta-Receptors, Adrenergic
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002614	Chelating Agents	Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS.	Chelating Agent,Chelator,Complexons,Metal Antagonists,Chelators,Metal Chelating Agents,Agent, Chelating,Agents, Chelating,Agents, Metal Chelating,Antagonists, Metal,Chelating Agents, Metal
D004533	Egtazic Acid	A chelating agent relatively more specific for calcium and less toxic than EDETIC ACID.	EGTA,Ethylene Glycol Tetraacetic Acid,EGATA,Egtazic Acid Disodium Salt,Egtazic Acid Potassium Salt,Egtazic Acid Sodium Salt,Ethylene Glycol Bis(2-aminoethyl ether)tetraacetic Acid,Ethylenebis(oxyethylenenitrile)tetraacetic Acid,GEDTA,Glycoletherdiamine-N,N,N',N'-tetraacetic Acid,Magnesium-EGTA,Tetrasodium EGTA,Acid, Egtazic,EGTA, Tetrasodium,Magnesium EGTA