EFFECTS OF EXOGENOUS LIPID APPLICATION ON EXCITABILITY OF APLYSIA NEURONS

DIETRICH BÜSSELBERG, DAVID O. CARPENTER, MUTSUMI SUGITA, SHIGEKO ARAKI, MEI SATAKE, HINRICH RAHMANN
1990 Biomedical research  
The electrophysiological effects of a variety of lipids on Aplysia neurons were determined using conventional two-electrode voltage-clamp recording techniques. Lipids, applied in concentration of 10"' M by pressure ejection from micropipettes, included a ganglioside mixture from bovine brain, cholesterol, lipid IV (a glucuronic acid-containing glycosphingolipid from spermatozoa of a fresh water bivalve) and SGL II (a diphosphonopentaosylceramide containing 3-methylgalactose from the skin of the
more » ... rom the skin of the marine snail /1p@1SI'G kurodai). All of the lipids induced currents in about 80% of the neurons. The responses to the different lipids were similar except that only gangliosides evoked a very rapid and sensitive response in about 5% of neurons, as previously described (7) . Upon using application pulses from 1.0 to 2.5 sec, the most common response was a small (0.5 to 5 nA), biphasic current, with an initial outward component followed by a larger slow inward current. While the initial component was not always voltage-dependent, the slow current varied with holding potentials. This current reached its maximum after the termination of the application pulse. There was considerable variation in the response from cell to cell, and not all neurons reacted to the different lipids in the same way. Unlike results obtained with pressure ejection of lipids, membrane properties of neurons were not altered with prolonged bath perfusion of any of the lipids tested in concentration of 10'6 M. The similarity of the responses to the different lipids probably reflects nonspecific changes in the electrical properties of the cell induced by incorporation of small amounts of these lipids into the cell membrane. In the animal kingdom, different types of acid-brates like worms, arthropods, molluscs etc.), ic glycosphingolipids have developed: sulpho-particularly from the marine snail Aplysia glycosphingolipids and sialo-glycosphingo-kurodai (1, 2) and the snail shellfish (17). lipids (gangliosides; Fig. 1 ) have been found Finally glucuronic acid-containing glycoonly in Deurerosromia (echinoderms and ver-sphingolipids have been detected both in deutebrates) (18, 41). Aminophosphonic acid-terostomian tissue (human peripheral nerves; containing glycosphingolipids have been iso-9) and protostomian tissue (spermatozoa of lated only from Prorosromia (lower inverte-the fresh water mussel Hyriopsis sc/ilegelii,
doi:10.2220/biomedres.11.77 fatcat:pgviqk4a3fbljptslpaquhes34