Intracellular acidification of the leech giant glial cell evoked by glutamate and aspartate

Intracellular pH homeostasis and serotonin-induced pH changes inCalliphorasalivary glands: the contribution of V-ATPase and carbonic anhydrase

“…We have observed, in Calliphora salivary glands, that removal of extracellular Na + leads to intracellular alkalinization, suggesting the presence of a Na + -dependent acid loader. Known Na + -dependent acid loaders are Na + -driven amino acid transporters (Kanai and Hediger, 2003), which have been shown to be present in insect Malpighian tubules (RuizSanchez and O'Donnell, 2006;Linton and O'Donnell, 2000;Maddrell et al, 1974) and, for example leech giant glial cells (Deitmer and Schneider, 1997). In the latter preparation, glutamate application causes an intracellular acidification due to Na + -driven glutamate uptake (Deitmer and Schneider, 1997).…”

“…Known Na + -dependent acid loaders are Na + -driven amino acid transporters (Kanai and Hediger, 2003), which have been shown to be present in insect Malpighian tubules (RuizSanchez and O'Donnell, 2006;Linton and O'Donnell, 2000;Maddrell et al, 1974) and, for example leech giant glial cells (Deitmer and Schneider, 1997). In the latter preparation, glutamate application causes an intracellular acidification due to Na + -driven glutamate uptake (Deitmer and Schneider, 1997). Our observation that removal of glutamate from the bath leads to an alkalinization similar to that following Na + removal suggests that Calliphora salivary glands may indeed contain a Na + -dependent glutamate transporter.…”

Intracellular Calcium Transients and Potassium Current Oscillations Evoked by Glutamate in Cultured Rat Astrocytes

“…The pH i measurements might have been impaired by the H ϩ permeability of the gramicidin pores (Myers and Haydon, 1972), which could have caused a dampening of the pH i changes. The mechanisms of this acidification are discussed elsewhere (Brune and Deitmer, 1995;Rose and Ransom, 1996;Deitmer and Schneider, 1997).…”

Glutamate receptor 5/6/7-like and glutamate transporter-1-like immunoreactivity in the leech central nervous system

“…The similarities in sequence and pharmacology of both vertebrate and invertebrate glutamate receptors thus justifies our use of GluR antibodies raised against vertebrate sequences in an invertebrate model. The same reasoning may be applied to the case of using antisera to vertebrate glutamate transporters in an invertebrate system, since vertebrate reuptake blockers have been found to be effective in the leech (Deitmer and Schneider, 1997). Thus far, sequence homology of vertebrate and invertebrate glutamate transporters has not been investigated.…”

“…Agonist-induced excitation of neuropil glia and DE-3 are also blocked by non-NMDA antago-nists (Deitmer and Munsch, 1992;Thorogood et al, 1996). Recently, Deitmer and Schneider (1997) have demonstrated that antagonists of glutamate transporter activity potentiate glutamate agonist-induced pH changes in neuropil glia. Taken together, these findings suggest a neurotransmitter role for glutamate in the leech CNS: mediating synaptic connections within the leech swim circuitry and from mechanosensory cells to their postsynaptic targets.…”