The regulation of intracellular pH by identified glial cells and neurones in the central nervous system of the leech

1. Double-barrelled, neutral-carrier pH-sensitive micro-electrodes were used to measure the intracellular pH (pHi) and the pHi regulation of neuropile glial (n.g.) cells and of identified neurones of the leech Hirudo medicinalis. 2. The distribution of H+ in the n.g. cells and in the neurones was found not to be in electrical equilibrium. The mean pHi of the n.g. cells was 6.87 +/- 0.13 (mean +/- S.D. of mean here and for all following data n = 27) in HEPES-buffered leech saline (pHo = 7.4) and 7.18 +/- 0.19 (n = 13) in 2% CO2-11 mM-HCO3(-)-saline. The mean pHi was 7.28 +/- 0.1 (n = 20) in Retzius neurones and 7.32 +/- 0.15 (n = 12) in noxious neurones in HEPES-buffered leech saline, and 7.20 +/- 0.15 (n = 10) and 7.27 +/- 0.16 (n = 6) in 2% CO2-11 mM-HCO3(-)-buffered saline in these two types of neurones, respectively. 3. The cytoplasmic buffering power, as calculated by the change in pHi following the change from 2% CO2-11 mM-HCO3- to 5% CO2-22 mM-HCO3- in the leech saline, was 20-30 mM/pH unit in the n.g. cells and between 12 and 33 mM/pH unit in the neurones. 4. The recovery of pHi in n.g. cells from an experimentally induced acidification (addition and removal of 20 mM-NH4Cl) was dependent on the presence of external Na+. Independent of the buffer system used, pHi recovery was inhibited when external Na+ was exchanged by N-methyl-D-glucamine. Amiloride (2-3 mM) reduced the rate of pHi recovery by about 50% in these n.g. cells. 5. In CO2-HCO3(-)-free saline, or in the presence of the anion exchange blocker 4-acetamido-4'-isothiocyanostilbene-2, 2'-disulphonic acid (SITS, 0.5 mM), pHi recovery from an acid load was often slowed by up to 50% in n.g. cells. This suggests that there is a significant contribution of a HCO3(-)-dependent membrane transport to pHi regulation in n.g. cells. 6. When a HEPES-buffered saline was exchanged by a 2% CO2-11 mM-HCO3(-)-buffered saline, the pHi of n.g. cells increased by 0.31 pH units. This alkaline shift was reversible upon removal of the CO2-HCO3- and was absent in the Na+-free saline. It was not inhibited by 1 mM-furosemide or by 0.5 mM-SITS.(ABSTRACT TRUNCATED AT 400 WORDS)

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

In the leech Hirudo medicinalis, pH-sensitive microelectrodes showed neuropile glial cells were more acidic than Retzius and noxious neurones, and pHi recovery from acid loads depended on Na+ and partly on amiloride-sensitive and bicarbonate-dependent transport.

Explore how this research connects to clinical practice

More peer-reviewed studies in Genomics & Proteomics.

• Leech Salivary Proteome and Transcriptome: 434 Deduced Protein Sequences — Liu Z, Tong X, Su Y, et al. (2019)
• Medicinal Leech Draft Genome — Anticoagulant Gene Survey — Kvist S, Manzano-Marín A, de Carle D, Trontelj P, Siddall ME (2020)
• Leech therapy (Hirudo medicinalis) attenuates testicular damages induced by testicular ischemia/reperfusion in an animal model — Davoodi F et al. (2021)
• New anticoagulant protein from medicinal leech — Manuvera V et al. (2024)
• AIF-1 and RNASET2 Play Complementary Roles in the Innate Immune Response of Medicinal Leech — Baranzini N et al. (2019)
• Medicinal leech antimicrobial peptides lacking toxicity represent a promising alternative strategy to combat antibiotic-resistant pathogens — Grafskaia E et al. (2019)
• Structural insights into thrombolytic activity of destabilase from medicinal leech — Marin E et al. (2023)
• The genome of medicinal leech (Whitmania pigra) and comparative genomic study for exploration of bioactive ingredients — Tong L et al. (2022)
• Medicinal Leech CNS as a Model for Exosome Studies in the Crosstalk between Microglia and Neurons — Raffo-Romero A et al. (2018)
• Transcriptomic profiling and the first spatial expression analysis of candidate genes in the salivary gland of the East Asian medicinal leech, Hirudo nipponia — Kim J et al. (2024)

Browse all ASH-analysed research →