The ion concentrations of body fluids in most invertebrates (except insects) are mostly due to the aequimolar concentrations of sodium and chloride. Among annelids this only holds true for polychaetes, while clitellates (oligochaetes and leeches) show a markedly reduced concentration of chloride (Oglesby, 1978).
In leeches, a relativly high concentration of carbonic acids, especially malate, contributes to the anion-cation balance (Niczaij, 1994). Under conditions of „biotopbedingter Anaerobiose“, the medical leech (Hirudo medicinales) uses malate for a fast energy supply (Zebe et al. 1981, Hildebrandt & Zerbst-Boroffka 1992, Schmidt et al. 1996). Hyperosmotic stress leads to a large accumulation of malate (Niezcaij & Zerbst-Boroffka, 1993), yet the function of this is unknown.
I am investigating these parameters in oligochaetes for to see if they are a general physiological feature in clitellats. I have chosen the common earthworm (Lumbricus terrestris) as a model.

Parameters under investigation:

• Carboxylic acids (HPLC; enzymatic)

 
• Anorganic anions (electrochemical chloride titration, CE)

 
• Kations (CE)

 
• Osmolality (Clifton Nanoliterosmometer, F-AAS)

 
• ATP, Amino acids (enzymatic)

LITERATUR :

Hildebrandt, J.P., Zerbst-Boroffka, I. (1992) Osmotic and ionic regulation during hypoxia in the medicinal leech, Hirudo medicinalis L. J.exp.Zool. 263, 374 - 381
Niczaj, R. , Zerbst-Boroffka, I. (1994) Low chlorid and high short-chain carboxylic acid concentration in extracellular fluid: a common physiological feature of the hirudinea. Can.J.Zool. 72, 1120 - 1125
Nieczaj, R. , Zerbst-Boroffka, I. (1993) Hyperosmotic acclimation in the leech, Hirudo medicinalis L.: energy metabolism, osmotic, ionic and volume regulation
Oglesby, L.C. (1978) Salt and water balance. In: Physiology of Annelids (ed. P.J.Mill), 555 - 658- New York: Academic Press
Schmidt, H., Wichman, A., Lamprecht, I., Zerbst-Boroffka, I. (1996) Anaerobic metabolism in the leech (Hirudo medicinalis L.): direct and indirect colorimetry during severe hypoxia. J.comp.Physiol. B 166, 205 - 214
Zebe, E. Salge, U., Wismann, C., Wilps, H. (1981) The energy metabolism or the leech Hirudo medicinalis in anoxia and muscular work. J.exp.Zool. 218, 157 - 163
 

POSTERABSTRACT
(DZG-Congress 1999, Innsbruck, Austria)