Cardinaud, B., Coles, J. A., Perrottet, P., Spencer, A. J., Osborne, M. P. and Tsacopoulos, M. (1994) The composition of the interstitial fluid in the retina of the honeybee drone: implications for the supply of substrates of energy metabolism from blood to neurons. Proceedings of the Royal Society of London Series B: Biological Sciences, 257(1348), pp. 49-58. (doi: 10.1098/rspb.1994.0093)
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Publisher's URL: http://dx.doi.org/10.1098/rspb.1994.0093
Abstract
Ion-selective microelectrodes were used to measure extracellular free ion concentrations in the retina of the drone honeybee, Apis mellifera male. Mean values were (in millimoles per litre): Na$^{+}$, 196; K$^{+}$, 10.2; Ca$^{2+}$, 2.0; pH 6.9. The elemental composition of fluid that rose into a micropipette inserted in the retina was obtained by electron microprobe X-ray analysis: from the concentrations of Na and K it was estimated that this fluid was 91% interstitial fluid. Amino acids and carbohydrates were analysed by chromatography. Four amino acids had concentrations > 20 mM: proline (109 mM), glutamine (38 mM), alanine (31 mM) and $\beta $-alanine (24 mM). These concentrations were higher than in the haemolymph. Other amino acids had concentrations of less than 3 mM. The identified carbohydrates were trehalose, glucose, pyruvate and fructose. All of these were less concentrated than in the haemolymph. These results: (i) show that the ion concentrations of previously used Ringer solutions were reasonably correct; (ii) demonstrate properties of the blood-retina barrier; (iii) suggest that the extracellular concentration of alanine is ample for it to serve as a major substrate of neuronal energy metabolism in this tissue.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Coles, Dr Jonathan |
Authors: | Cardinaud, B., Coles, J. A., Perrottet, P., Spencer, A. J., Osborne, M. P., and Tsacopoulos, M. |
College/School: | College of Medical Veterinary and Life Sciences > School of Infection & Immunity |
Journal Name: | Proceedings of the Royal Society of London Series B: Biological Sciences |
Publisher: | The Royal Society |
ISSN: | 0962-8452 |
ISSN (Online): | 1471-2954 |
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