Biomaterial Database

Effect of lowered extracellular pH on Ca2(+)-dependent K+ currents in type I cells from the neonatal rat carotid body. 1990

C Peers

University Laboratory of Physiology, Oxford.

1. The whole-cell configuration of the patch-clamp technique was used to record K+ currents from type I cells enzymatically dispersed from the neonatal rat carotid body. The current-voltage (I-V) relationship for the K+ currents showed a prominent, outward shoulder at test potentials of between +10 and +30 mV. 2. The shoulder of the I-V curve could be enhanced by raising extracellular Ca2+ concentration or by bath application of 5 microM-Bay K 8644. It could also be suppressed by bath application of 100 microM-Cd2+ or 5 microM-methoxyverapamil (D600), indicating that a large component of the K+ current in these cells was activated by an influx of Ca2+ through its own channels during cell depolarization. 3. Potassium currents were also reversibly suppressed by 8 nM-charybdotoxin but unaffected by 100 nM-apamin, suggesting that the Ca2(+)-dependent K+ current was carried through large or intermediate conductance Ca2(+)-activated K+ channels. 4. Lowering the pH of the bathing medium from 7.40 to 7.00 reversibly reduced the K+ current amplitudes, and suppressed the shoulder normally seen in the I-V relationship. This effect was enhanced in the presence of 5 microM-Bay K 8644 and abolished in the presence of 5 microM-D600. 5. It is concluded that the Ca2(+)-dependent K+ channels of type I carotid body cells are selectively suppressed by extracellular acidity. Possible mechanisms underlying this effect, and its role in excitation of the carotid body are discussed.

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
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.
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
D002344	Carotid Body	A small cluster of chemoreceptive and supporting cells located near the bifurcation of the internal carotid artery. The carotid body, which is richly supplied with fenestrated capillaries, senses the pH, carbon dioxide, and oxygen concentrations in the blood and plays a crucial role in their homeostatic control.	Glomus Caroticum,Bodies, Carotid,Body, Carotid,Caroticum, Glomus,Carotid Bodies
D005711	Gallopamil	Coronary vasodilator that is an analog of iproveratril (VERAPAMIL) with one more methoxy group on the benzene ring.	Methoxyverapamil,D-600,D600,Elgiprona,Gallobeta,Gallopamil Hydrochloride,Prebet,Procorum,gallopamil von ct,D 600,Hydrochloride, Gallopamil
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
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
D000831	Animals, Newborn	Refers to animals in the period of time just after birth.	Animals, Neonatal,Animal, Neonatal,Animal, Newborn,Neonatal Animal,Neonatal Animals,Newborn Animal,Newborn Animals
D001030	Apamin	A highly neurotoxic polypeptide from the venom of the honey bee (Apis mellifera). It consists of 18 amino acids with two disulfide bridges and causes hyperexcitability resulting in convulsions and respiratory paralysis.