Biomaterial Database

Influence of anomalous rectifier activation on afterhyperpolarizations of neurons from cat sensorimotor cortex in vitro. 1988

P C Schwindt, and W J Spain, and W E Crill

Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle 98195.

1. Large neurons from layer V of cat sensorimotor cortex (Betz cells) were studied to determine the influence of the anomalous rectifier current (IAR) on slow afterhyperpolarizations (AHPs). The neurons were examined using intracellular recording and single-microelectrode voltage clamp in an in vitro brain slice preparation. 2. A faster medium-duration AHP (mAHP) and slower AHP (sAHP) followed repetitive firing (22, 23). The amplitude of the mAHP often increased or remained constant during membrane potential hyperpolarization. The membrane potential trajectory resulting solely from IAR activation was similar to the mAHP. 3. Postrepetitive firing voltage clamp was used to measure directly slowly decaying K+ currents (IK) and IAR at different membrane potentials. IK exhibited both a fast and slow decay. The time constants of the fast decay of IK and IAR activation were similar. IAR increased with hyperpolarization or raised extracellular K+ concentration [( K+]o), whereas both the fast and slow components of IK reversed or nulled near -100 mV and behaved as pure K+ currents in response to raised [K+]o. 4. To determine the precise contribution of IK and IAR to the AHP waveform, theoretical AHPs were computed using a quantitative model based on voltage-clamp measurements. The calculated AHPs were qualitatively similar to measured AHPs. The amplitude of the mAHP showed little change with hyperpolarization because of the increasing dominance of IAR at more negative membrane potentials. The sAHP was little affected by IAR activation. 5. Several model parameters subject to biological variation among Betz cells were varied in the calculations to determine their importance in the AHP waveform. With IK parameters held constant, the amplitude and time course of the mAHP depended on resting potential, membrane time constant, the kinetics of the anomalous rectifier conductance (GAR), and the maximum value of GAR. IAR activation could result in a biphasic AHP even when the fast decay of IK was omitted from the calculations. 6. A wider variation of model parameters revealed behavior that may be relevant to other neurons. Certain values of membrane or IAR activation time constants resulted in a monophasic AHP even when the fast decay of IK was present. The decay of a biphasic AHP could reflect either the onset of IAR or the fast decay of IK, depending on the relative value of their time constants. Procedures are outlined to discriminate between these possibilities using current clamp methods.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
D008959	Models, Neurological	Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Neurologic Models,Model, Neurological,Neurologic Model,Neurological Model,Neurological Models,Model, Neurologic,Models, Neurologic
D009044	Motor Cortex	Area of the FRONTAL LOBE concerned with primary motor control located in the dorsal PRECENTRAL GYRUS immediately anterior to the central sulcus. It is comprised of three areas: the primary motor cortex located on the anterior paracentral lobule on the medial surface of the brain; the premotor cortex located anterior to the primary motor cortex; and the supplementary motor area located on the midline surface of the hemisphere anterior to the primary motor cortex.	Brodmann Area 4,Brodmann Area 6,Brodmann's Area 4,Brodmann's Area 6,Premotor Cortex and Supplementary Motor Cortex,Premotor and Supplementary Motor Cortices,Anterior Central Gyrus,Gyrus Precentralis,Motor Area,Motor Strip,Precentral Gyrus,Precentral Motor Area,Precentral Motor Cortex,Premotor Area,Premotor Cortex,Primary Motor Area,Primary Motor Cortex,Secondary Motor Areas,Secondary Motor Cortex,Somatic Motor Areas,Somatomotor Areas,Supplementary Motor Area,Area 4, Brodmann,Area 4, Brodmann's,Area 6, Brodmann,Area 6, Brodmann's,Area, Motor,Area, Precentral Motor,Area, Premotor,Area, Primary Motor,Area, Secondary Motor,Area, Somatic Motor,Area, Somatomotor,Area, Supplementary Motor,Brodmann's Area 6s,Brodmanns Area 4,Brodmanns Area 6,Central Gyrus, Anterior,Cortex, Motor,Cortex, Precentral Motor,Cortex, Premotor,Cortex, Primary Motor,Cortex, Secondary Motor,Cortices, Secondary Motor,Gyrus, Anterior Central,Gyrus, Precentral,Motor Area, Precentral,Motor Area, Primary,Motor Area, Secondary,Motor Area, Somatic,Motor Areas,Motor Cortex, Precentral,Motor Cortex, Primary,Motor Cortex, Secondary,Motor Strips,Precentral Motor Areas,Precentral Motor Cortices,Premotor Areas,Primary Motor Areas,Primary Motor Cortices,Secondary Motor Area,Secondary Motor Cortices,Somatic Motor Area,Somatomotor Area,Supplementary Motor Areas
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
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.
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
D013003	Somatosensory Cortex	Area of the parietal lobe concerned with receiving sensations such as movement, pain, pressure, position, temperature, touch, and vibration. It lies posterior to the central sulcus.	Brodmann Area 1,Brodmann Area 2,Brodmann Area 3,Brodmann Areas 1, 2, 3,Brodmann Areas 1, 2, and 3,Brodmann Areas 3, 1, 2,Brodmann Areas 3, 1, and 2,Brodmann's Area 1,Brodmann's Area 2,Brodmann's Area 3,Brodmann's Areas 1, 2, and 3,Brodmann's Areas 3, 1, and 2,Parietal-Opercular Cortex,Primary Somesthetic Area,S1 Cortex,S2 Cortex,SII Cortex,Anterior Parietal Cortex,Gyrus Postcentralis,Post Central Gyrus,Postcentral Gyrus,Primary Somatic Sensory Area,Primary Somatosensory Area,Primary Somatosensory Areas,Primary Somatosensory Cortex,SI Cortex,Second Somatic Sensory Area,Secondary Sensory Cortex,Secondary Somatosensory Area,Secondary Somatosensory Cortex,Area 1, Brodmann,Area 1, Brodmann's,Area 2, Brodmann,Area 2, Brodmann's,Area 3, Brodmann,Area 3, Brodmann's,Area, Primary Somatosensory,Area, Primary Somesthetic,Area, Secondary Somatosensory,Areas, Primary Somatosensory,Brodmanns Area 1,Brodmanns Area 2,Brodmanns Area 3,Cortex, Anterior Parietal,Cortex, Parietal-Opercular,Cortex, Primary Somatosensory,Cortex, S1,Cortex, S2,Cortex, SI,Cortex, SII,Cortex, Secondary Sensory,Cortex, Secondary Somatosensory,Cortex, Somatosensory,Gyrus, Post Central,Gyrus, Postcentral,Parietal Cortex, Anterior,Parietal Opercular Cortex,Parietal-Opercular Cortices,Primary Somatosensory Cortices,Primary Somesthetic Areas,S1 Cortices,S2 Cortices,SII Cortices,Secondary Somatosensory Areas,Sensory Cortex, Secondary,Somatosensory Area, Primary,Somatosensory Area, Secondary,Somatosensory Areas, Primary,Somatosensory Cortex, Primary,Somatosensory Cortex, Secondary,Somesthetic Area, Primary,Somesthetic Areas, Primary
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In