Extracellular free calcium and potassium during paroxysmal activity in the cerebral cortex of the cat
Tóm tắt
Extracellular calcium and potassium activities (aCa and aK) as well as neuronal activity were simultaneously recorded with ion-sensitive electrodes in the somatosensory cortex of cats. Baseline aCa was 1.2–1.5 mM/1, baseline a
k
2.7–3.2 mM/1. Transient decreases in aCa and simultaneous increases in aK were evoked by repetitive stimulation of the contralateral forepaw, the nucleus ventroposterolateralis thalami and the cortical surface. Considerable decreases in aCa (by up to 0.7 mM/1) were found during seizure activity. A fall in aCa preceded the onset of paroxysmal discharges and the rise in aK after injection of pentylene tetrazol. The decrease in aCa led also the rise in aK during cyclical spike driving in a penicillin focus. It is concluded that alterations of Ca++ dependent mechanisms participate in the generation of epileptic activity.
Tài liệu tham khảo
Ames, A., Sakanoue, M., Endo, S.: Na, K, Ca, Mg, and Cl concentrations in choroid plexus fluid and cisternal fluid compared with plasma ultrafiltrate. J. Neurophysiol. 27, 672–681 (1964)
Eckert, R., Lux, H.D.: A voltage-sensitive persistant calcium conductance in neuronal somata of helix. J. Physiol. (Lond.) 254, 129–151 (1976)
Frankenhaeuser, B., Hodgkin, A.L.: The action of calcium in the electrical properties of squid axons. J. Physiol. (Lond.) 137, 218–244 (1957)
Fisher, R.S., Pedley, T.A., Moody, W.J., Prince, D.A.: The role of extracellular potassium in hippocampal epilepsy. Arch. Neurol. (Chic.) 33, 76–83 (1976)
Heinemann, U., Lux, H.D.: Undershoots following stimulus induced rises of extracellular potassium concentration in cerebral cortex of cat. Brain Res. 93, 63–76 (1975)
Heinemann, U., Lux, H.D.: “Ceiling” of rises in extracellular potassium activity in the cerebral cortex of cats. Brain Res. 120, 231–250 (1977)
Heinemann, U., Gutnick, M.J., Lux, H.D.: Field potentials and focal changes in extracellular potassium concentration in a specific thalamic nucleus. Pflügers Arch. 362, R36 (1976)
Heyer, C.B., Lux, H.D.: Properties of facilitating calcium current in pacemaker neurons of the snail, Helix pomatia. J. Physiol. (Lond.) 262, 319–348 (1976)
Hodgkin, A.C., Horowicz, D.: The influence of potassium and chloride ions on the membrane potential of single muscle fibers. J. Physiol. (Lond.) 148, 127–160 (1959)
Katz, B.: The release of neural transmitter substances. The Sherrington Lectures. Springfield, USA: Charles C. Thomas 1969
Liebl, L., Lux, H.D.: The action of Ca++, Ba++ and Verapanil on anomalous rectification in cat spinal motoneurons. Pflügers Arch. 335, R80 (1975)
Llinás, R., Hess, R.: Tetrodotoxin-resistant dendritic spikes in avian Purkinje cells. Proc. nat. Acad. Sci. (Wash.) 73, 2520–2523 (1976)
Lux, H.D.: Fast recording ion specific electrodes. Their use in pharmacological studies in the CNS. Neuropharmacol. 13, 509–517 (1974)
Lux, H.D.: Kinetics of extracellular potassium: relation to epileptogenesis. Epilepsia (Boston) 15, 375–393 (1974)
Lux, H.D., Neher, E.: The equilibration time course of (K+)o in cat cortex. Exp. Brain Res. 17, 190–205 (1973)
Lux, H.D., Schubert, P.: Some aspects of the electroanatomy of dendrites. Advances in Neurology, Vol. 12 (ed. G.W. Kreutzberg), 1975
Meech, R.W., Standen, N.B.: Potassium activation in Helix asperga under voltage clamp: a component mediated by calcium influx. J. Physiol. (Lond.) 249, 211–239 (1975)
Nicholson, C., Ten Bruggencate, G., Steinberg, R., Stöckle, H.: Calcium modulation in brain extracellular microenvironment demonstrated with ion-selective micropipette. Proc. nat. Acad. Sci. (Wash.) (in press)
Moody, W.J., Jr., Futamachi, K.J., Prince, D.A.: Extracellular potassium activity during epileptogenesis. Exp. Neurol. 42, 248–263 (1974)
Oehme, M., Kessler, M., Simon, W.: Neutral Carrier Ca++-Mikroelektrode. Chimia 30, 204–206 (1976)
Prince, D.A.: Cortical cellular activities during cyclically occuring interictal epileptiform discharges. Electroenceph. clin. Neurophysiol. 31, 469–484 (1971)
Prince, D.A., Lux, H.D., Neher, E.: Measurements of extracellular potassium activity in cat cortex. Brain Res. 50, 489–495 (1973)
Sypert, G.W., Ward, A.A., Jr.: Changes in extracellular potassium activity during neocortical propagated seizures. Exp. Neurol. 45, 19–41 (1974)
Walker, G.L., Jr.: Ion specific liquid ion exchanger microelectrodes. Anal. Chem. 43, 89A-92A (1971)
Williamson, T.L., Crill, W.E.: The effect of pentylene tetrazole on molluscan neurons. II. Voltage clamp studies. Brain Res. 116, 231–249 (1976)