Biomaterial Database

Two distinct Ca-dependent K currents in bullfrog sympathetic ganglion cells. 1985

P Pennefather, and B Lancaster, and P R Adams, and R A Nicoll

Healthy bullfrog sympathetic ganglion cells often show a two-component afterhyperpolarization (AHP). Both components can be reduced or abolished by adding Ca-channel blockers or by removing external Ca. Application of a single electrode "hybrid clamp"--i.e., switching from current- to voltage-clamp at the peak of the AHP, reveals that the slow AHP component is generated by a small, slow, monotonically decaying outward current, which we call IAHP. IAHP is blocked by Ca-removal or by apamin and is a pure K current. It is slightly sensitive to muscarine and to tetraethylammonium ion but is much less so than muscarine-sensitive (IM) and fast Ca-dependent (IC) K currents. It also can be recorded in dual-electrode voltage-clamp experiments, where it is seen as a slow, small component of the outward tail current that follows brief depolarizations to 0 mV or beyond. IC is seen as an early, fast, large component of the same tail current. Both components are blocked by Ca removal, but only the IC component is blocked by low doses of tetraethylammonium ion. Thus, bullfrog ganglion cells exhibit two quite distinct Ca-dependent K currents, which differ in size, voltage-sensitivity, kinetics, and pharmacology. These two currents also play quite separate roles in shaping the action potential.

UI	MeSH Term	Description	Entries
D007473	Ion Channels	Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.	Membrane Channels,Ion Channel,Ionic Channel,Ionic Channels,Membrane Channel,Channel, Ion,Channel, Ionic,Channel, Membrane,Channels, Ion,Channels, Ionic,Channels, Membrane
D009116	Muscarine	A toxic alkaloid found in Amanita muscaria (fly fungus) and other fungi of the Inocybe species. It is the first parasympathomimetic substance ever studied and causes profound parasympathetic activation that may end in convulsions and death. The specific antidote is atropine.
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011892	Rana catesbeiana	A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.	Bullfrog,Bullfrogs,Rana catesbeianas,catesbeiana, Rana
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
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.
D005728	Ganglia, Sympathetic	Ganglia of the sympathetic nervous system including the paravertebral and the prevertebral ganglia. Among these are the sympathetic chain ganglia, the superior, middle, and inferior cervical ganglia, and the aorticorenal, celiac, and stellate ganglia.	Celiac Ganglia,Sympathetic Ganglia,Celiac Ganglion,Ganglion, Sympathetic,Ganglia, Celiac,Ganglion, Celiac,Sympathetic Ganglion
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013757	Tetraethylammonium Compounds	Quaternary ammonium compounds that consist of an ammonium cation where the central nitrogen atom is bonded to four ethyl groups.	Tetramon,Tetrylammonium,Compounds, Tetraethylammonium