QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by HENDY, C. H. Articles by DJAMGOZ, M. B. A. Search for Related Content PubMed Articles by HENDY, C. H. Articles by DJAMGOZ, M. B. A.

Journal of Experimental Biology 127,211-227 (1987)
Published by Company of Biologists 1987

Potassium Activity Measurements in the Microenvironment of the Central Nervous System of an Insect

C. H. HENDY ¹ and M. B. A. DJAMGOZ ¹

¹ Department of Pure and Applied Biology, Neuroscience Group, Imperial College, London SW7 2BB

The activity of K⁺ and the control of influx of ⁺ into the extracellular space (micro-environment) of the central nervous system of the cockroach, Periplaneta americana, were measured directly with K⁺-sensitive microelectrodes. Using an in vivo preparation, it was possible to follow the effects of changes in K⁺ concentration in the medium bathing the nervous system on extracellular K⁺ and spontaneous and evoked neuronal activity. For bath K⁺ levels less than 31 mmoll^-1, roughly corresponding to maximal haemolymph level in natural physiological conditions, the blood-brain barrier was found to be suitably efficient in restricting the influx of K⁺ and thereby allowing normal neural activity. At an external K⁺ concentration of 100 mmoll^-1, however, the system was unable to maintain a sufficiently low extracellular K⁺ concentration and neuronal activity was suppressed. Influx of K⁺ from the external medium into the micro-environment occurred mainly in two phases. The early phase had a fast time course and probably reflects the physical aspects of the blood-brain barrier. The later, second phase was a slower process possibly corresponding to activation of metabolic ion pumps. The time courses of the functioning of these two systems and their control of the extraaxonal K⁺ activity are also discussed.

Key words: blood-brain barrier, extracellular potassium, ion-sensitive microelectrodes, Periplaneta americana

Accepted on August 27, 1986

This article has been cited by other articles:

				A. R. Goriely, T. W. Secomb, and L. P. Tolbert Effect of the Glial Envelope on Extracellular K+ Diffusion in Olfactory Glomeruli J Neurophysiol, April 1, 2002; 87(4): 1712 - 1722. [Abstract] [Full Text] [PDF]