Osmotic and ionic regulation during hypoxia in the medicinal leech, <i>Hirudo medicinalis</i> L.

Hildebrandt, Jan‐Peter; Zerbst‐Boroffka, Irene

doi:10.1002/jez.1402630405

Cited by 10 publications

(4 citation statements)

References 19 publications

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“…[Mg 2+ ] T in leech blood as determined by atomic absorption spectrometry has a mean ± SD of 1.64 ± 0.52 mmol/l (n = 3, unpublished results). At an extracellular malate concentration of 30 mmol/l and a K app of 15.5 mmol/l, as determined in the present study, this corresponds to a [Mg 2+ ] o of 0.57 ± 0.18 mmol/l, which is in excellent agreement with the [Mg 2+ ] o of 0.6 ± 0.2 mmol/l determined by Hildebrandt & Zerbst-Boroffka (12). [Mg 2+ ] o in the leech is thus strongly buffered.…”

Section: Biological Relevance Of the Bindingsupporting

confidence: 91%

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Use of Mg2+ and Ca2+ macroelectrodes to measure binding in extracellular-like physiological solutions

Günzel

McGuigan²,

Schlue³

2005

Front Biosci

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Macroelectrodes designed to measure the extracellular free Mg2+ and Ca2+ concentrations ([Mg2+]o, [Ca2+]o) may be used to determine Mg2+ and Ca2+ binding to extracellular buffers. This is important, as buffer concentrations may change physiologically or experimentally. A simplified calibration method allowed [Mg2+]o and [Ca2+]o > 50 micromol/l to be accurately measured. The method was used to determine the apparent dissociation constant, Kapp (+/- SD) of Mg2+ binding to aspartate (22 degrees C, 101.7 +/- 22.5 mmol/l, n = 8; 44 degrees C, 45.2 +/- 8.3 mmol/l, n = 6), citrate (high affinity, 0.33 +/- 0.14 mmol/l, n = 4; low affinity, approximately 80 mmol/l), malate (15.9 +/- 1.0 mmol/l, n = 7) and Ca2+ binding to malate (10.3 +/- 1.1 mmol/l, n = 7). Calculated and measured Kapp for Ca2+ binding to malate were only in agreement if the concept of ionic equivalent was used to adapt the tabulated constants to the experimental conditions. For Mg2+ binding to aspartate, malate and citrate there was no or only limited agreement with the calculated Kapp. These findings emphasise the difficulties involved in calculating free concentrations in biological solutions. It is concluded that it is more accurate to measure Kapp at the appropriate ionic strength and temperature.

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Section: Biological Relevance Of the Bindingsupporting

confidence: 91%

“…From equation [4], the ratio of the concentrations is: [12] [X-Anion (n -2)-]: Substituting for [Anion n-] from equation [12] in equation [10] gives [25] Substitution of equations [20] and [21] in equation [25] [27] Substitution of equations [20] and [21] in equation [27] [ [30] [X 2+ ]: Substituting equations [20] and [21] in equation [22]:…”

Section: Discussionmentioning

confidence: 99%

Use of Mg2+ and Ca2+ macroelectrodes to measure binding in extracellular-like physiological solutions

Günzel

McGuigan²,

Schlue³

2005

Front Biosci

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“…This species might be more tolerant to low oxygen partial pressure. Hildebrandt & Zerbst (1992) found that sodium concentrations in the blood of medicinal leeches decreased significantly after 96 h in hypoxia. However, sodium levels in a brackish water isopod were found not to be affected by hypoxia and Na + concentrations decreased only in anoxia (Hagerman & Szaniawska, 1991).…”

Section: Discussionmentioning

confidence: 97%

Tolerance of Three European Native Species of Crayfish to Hypoxia

et al. 2006

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Species that can act as indicators of ecosystem health offer a valuable tool in the management of natural resources. Crayfish have been suggested as bioindicators of water quality in Europe and at least one species (Austropotamobius pallipes) has been studied to determine its tolerance to pollution and its potential as a bioindicator. The genus Austropotamobius includes three crayfish species native to western Europe: A. pallipes, A. italicus and A. torrentium. It was hypothesised that because of their geographical and habitat distribution, the three Austropotamobius species might vary in their value as a bioindicator of water quality. Crayfish of species A. pallipes and A. italicus were subjected to three different treatments: hypoxia (treatment 3, approx 3 mg l )1 O 2 ), light hypoxia (treatment 2, approx 5.5 mg l )1 O 2 ) and normoxia (treatment 1, control, approx 8.5 mg l )1 O 2 ). A. torrentium crayfish were only subjected to treatment 1 (control) and 3. Variations in haemolymph sodium, calcium and chloride were used as a biomarker and concentrations were measured before and after treatment to evaluate hypoxia-induced stress. Significant differences in the concentrations of sodium between the control groups (treatment 1, normoxia) and the experimental groups (treatment 3, 3 mg l )1 O 2 ) were found in the species A. pallipes and A. torrentium. Groups of A. italicus did not show any significant difference between treatments in sodium concentrations but in chloride concentrations. Crayfish of all three species demonstrated a disruption in the ion exchange process in hypoxia, but all tolerated very low oxygen concentration for an extended period of time.

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“…Cl − is the major strong anion in all physiological saline environments for vertebrates, with bicarbonate as the major (anionic) buffer, but is partially replaced by organic anions in many invertebrates (Prosser and Brown, 1961), such as malate in the medicinal leech (Hildebrandt and Zerbst‐Boroffka, 1992). All living cells express a combination of transporters and ion channels to move Cl − , bicarbonate, and other anions across cell membranes.…”

Section: Introductionmentioning

confidence: 99%

Anion channels in astrocytes: Biophysics, pharmacology, and function

Kimelberg

MacVicar

Sontheimer

2006

Glia

112

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The chloride/anion channels that have been so far identified in cultured astrocytes and those that have been confirmed in situ by a combination of mRNA identification, immunocyto-chemistry, and biophysical studies are reviewed. It is emphasized that we are just beginning to describe such channels and analyze their functions in astrocytes. The best-studied anion channels studied so far are those known as volume-regulated anion channels (VRACs). These, as for most channels, have been mainly studied in cultured astrocytes, but some correlative studies have been done in situ, because these channels have been emphasized as release routes for transmitters; namely, excitatory amino acids and ATP. They are activated by cell shape changes and cell swelling, and the release of amino acids and ATP and chloride currents, measured by whole cell clamping, by these processes has been well described, as is also their activation by low concentrations of extracellular ATP. However, the identity of these channels in astrocytes, as in all other cells, remains elusive. The potential involvement of VRACs in pathological states such as stroke, metastasis, and spreading depression is also discussed.

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Osmotic and ionic regulation during hypoxia in the medicinal leech, Hirudo medicinalis L.

Cited by 10 publications

References 19 publications

Use of Mg2+ and Ca2+ macroelectrodes to measure binding in extracellular-like physiological solutions

Use of Mg2+ and Ca2+ macroelectrodes to measure binding in extracellular-like physiological solutions

Tolerance of Three European Native Species of Crayfish to Hypoxia

Anion channels in astrocytes: Biophysics, pharmacology, and function

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