Biomaterial Database

Electrophysiological changes of CA1 pyramidal neurons following transient forebrain ischemia: an in vivo intracellular recording and staining study. 1996

Z C Xu, and W A Pulsinelli

Department of Neurology, University of Tennessee, Memphis 38163, USA.

1. Electrophysiological changes of CA1 pyramidal neurons in rat hippocampus were studied before, during 5 min forebrain ischemia, and after reperfusion using in vivo intracellular recording and staining techniques. 2. membrane input resistance of CA1 neurons decreased from 25.98 +/- 7.24 M omega (mean +/- SD, n = 42) before ischemia to 16.33 +/- 6.50 M omega shortly after the onset of ischemia (n = 6, P < 0.01). The input resistance fell to zero during ischemic depolarization and quickly returned to 24.42 +/- 10.36 M omega (n = 11) within 2 h after reperfusion. 3. The time constant of CA1 neurons decreased from 11.49 +/- 5.45 ms (n = 36) to 3.09 +/- 1.66 ms (n = 6, P < 0.01) during ischemia. The time constant remained significantly less than preischemic levels within 2 h after reperfusion (5.40 +/- 2.60 ms, n = 13, P < 0.01) and gradually returned to preischemic levels 4-5 h after reperfusion. 4. The spike height decreased from 91 +/- 10.35 mV (n = 45) before ischemia to 82 +/- 8.00 mV (n = 9, P < 0.05) within 2 h after reperfusion and fully returned to preischemic level 2-5 h after reperfusion. The spike width increased from 1.14 +/- 0.22 ms (n = 45) before ischemia to 1.36 +/- 0.22 ms (n = 9, P < 0.05) within 2 h after reperfusion and remained at this level 4-5 h after reperfusion. 5. The spike threshold significantly increased from -54 +/- 3.93 mV (n = 45) before ischemia to -49 +/- 5.04 mV (n = 8, P < 0.01) within 2 h after reperfusion. The rheobase increased accordingly from 0.34 +/- 0.16 nA (n = 41) to 0.73 +/- 0.26 nA (n = 6, P < 0.01). The spike threshold returned to control levels 4-5 h after reperfusion, while the rheobase was still significantly higher than control levels (0.50 +/- 0.21 nA, n = 16, P < 0.01). 6. The frequency of repetitive firing evoked by depolarizing current pulses was suppressed within 2 h after reperfusion (n = 6, P < 0.01). The spike frequency increased slightly 2-5 h after reperfusion but was still significantly below the control levels (n = 12, P < 0.01). 7. Spontaneous synaptic activities ceased during ischemia and remained depressed shortly after reperfusion. Spontaneous firing rate was 0.47 +/- 0.81 spikes/s (n = 34) before ischemia. No spontaneous firing was detected within 2 h after reperfusion, and the firing rate gradually returned to preischemic levels 2-5 h after reperfusion (0.28 +/- 0.96 spikes/s, n = 15). Neuronal hyperactivity as indicated by an increased spontaneous firing rate was not observed up to 7 h after reperfusion. 8. Stimulation of the contralateral commissural pathway elicited excitatory postsynaptic potentials (EPSPs) minutes after reperfusion, whereas inhibitory postsynaptic potentials (IPSPs) did not appear until approximately 1 h after reperfusion. Within 2 h after reperfusion, the amplitudes of EPSPs slightly increased compared with those before ischemia, and the duration of EPSPs significantly increased from 18.00 +/- 3.08 ms (n = 5) before ischemia to 26.83 +/- 4.26 ms (n = 6, P < 0.01). The amplitude and duration of EPSPs returned to preischemic levels 4-5 h after reperfusion. 9. Results from the present study indicate that the input resistance and time constant of CA1 pyramidal neurons decrease during cerebral ischemia. After 5 min of forebrain ischemia, the spontaneous neuronal activities, evoked synaptic potentials and excitability of CA1 neurons are transiently suppressed after reperfusion. No hyperactivity was observed up to 7 h after reperfusion.

UI	MeSH Term	Description	Entries
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
D001784	Blood Gas Analysis	Measurement of oxygen and carbon dioxide in the blood.	Analysis, Blood Gas,Analyses, Blood Gas,Blood Gas Analyses,Gas Analyses, Blood,Gas Analysis, Blood
D002546	Ischemic Attack, Transient	Brief reversible episodes of focal, nonconvulsive ischemic dysfunction of the brain having a duration of less than 24 hours, and usually less than one hour, caused by transient thrombotic or embolic blood vessel occlusion or stenosis. Events may be classified by arterial distribution, temporal pattern, or etiology (e.g., embolic vs. thrombotic). (From Adams et al., Principles of Neurology, 6th ed, pp814-6)	Brain Stem Ischemia, Transient,Cerebral Ischemia, Transient,Crescendo Transient Ischemic Attacks,Transient Ischemic Attack,Anterior Circulation Transient Ischemic Attack,Brain Stem Transient Ischemic Attack,Brain TIA,Brainstem Ischemia, Transient,Brainstem Transient Ischemic Attack,Carotid Circulation Transient Ischemic Attack,Posterior Circulation Transient Ischemic Attack,TIA (Transient Ischemic Attack),Transient Ischemic Attack, Anterior Circulation,Transient Ischemic Attack, Brain Stem,Transient Ischemic Attack, Brainstem,Transient Ischemic Attack, Carotid Circulation,Transient Ischemic Attack, Posterior Circulation,Transient Ischemic Attack, Vertebrobasilar Circulation,Transient Ischemic Attacks, Crescendo,Vertebrobasilar Circulation Transient Ischemic Attack,Attack, Transient Ischemic,Attacks, Transient Ischemic,Brainstem Ischemias, Transient,Cerebral Ischemias, Transient,Ischemia, Transient Brainstem,Ischemia, Transient Cerebral,Ischemias, Transient Brainstem,Ischemias, Transient Cerebral,Ischemic Attacks, Transient,TIA, Brain,TIAs (Transient Ischemic Attack),Transient Brainstem Ischemia,Transient Cerebral Ischemia,Transient Cerebral Ischemias,Transient Ischemic Attacks
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
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.
D005071	Evoked Potentials	Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported.	Event Related Potential,Event-Related Potentials,Evoked Potential,N100 Evoked Potential,P50 Evoked Potential,N1 Wave,N100 Evoked Potentials,N2 Wave,N200 Evoked Potentials,N3 Wave,N300 Evoked Potentials,N4 Wave,N400 Evoked Potentials,P2 Wave,P200 Evoked Potentials,P50 Evoked Potentials,P50 Wave,P600 Evoked Potentials,Potentials, Event-Related,Event Related Potentials,Event-Related Potential,Evoked Potential, N100,Evoked Potential, N200,Evoked Potential, N300,Evoked Potential, N400,Evoked Potential, P200,Evoked Potential, P50,Evoked Potential, P600,Evoked Potentials, N100,Evoked Potentials, N200,Evoked Potentials, N300,Evoked Potentials, N400,Evoked Potentials, P200,Evoked Potentials, P50,Evoked Potentials, P600,N1 Waves,N2 Waves,N200 Evoked Potential,N3 Waves,N300 Evoked Potential,N4 Waves,N400 Evoked Potential,P2 Waves,P200 Evoked Potential,P50 Waves,P600 Evoked Potential,Potential, Event Related,Potential, Event-Related,Potential, Evoked,Potentials, Event Related,Potentials, Evoked,Potentials, N400 Evoked,Related Potential, Event,Related Potentials, Event,Wave, N1,Wave, N2,Wave, N3,Wave, N4,Wave, P2,Wave, P50,Waves, N1,Waves, N2,Waves, N3,Waves, N4,Waves, P2,Waves, P50
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
D013569	Synapses	Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.	Synapse
D015424	Reperfusion	Restoration of blood supply to tissue which is ischemic due to decrease in normal blood supply. The decrease may result from any source including atherosclerotic obstruction, narrowing of the artery, or surgical clamping. It is primarily a procedure for treating infarction or other ischemia, by enabling viable ischemic tissue to recover, thus limiting further necrosis. However, it is thought that reperfusion can itself further damage the ischemic tissue, causing REPERFUSION INJURY.	Reperfusions