Nifedipine‐ and omega‐conotoxin‐sensitive Ca2+ conductances in guinea‐pig substantia nigra pars compacta neurones
Abstract
1. The membrane properties of substantia nigra pars compacta (SNc) neurones were recorded in guinea-pig in vitro brain slices. 2. In the presence of tetrodotoxin (TTX) a Ca(2+)-dependent slow oscillatory potential (SOP) was generated. Application of 0.5-20 microM nifedipine abolished both spontaneous and evoked SOPs. A tetraethylammonium chloride (TEA)-promoted high-threshold Ca2+ spike (HTS) was little affected by nifedipine. On the other hand, omega-conotoxin applied either locally or via the perfusion medium (1-10 microM) blocked a part of the HTS, but it did not alter the SOP. 3. In normal medium nifedipine blocked the spontaneous discharge, decreased the interspike interval (ISI) recorded during depolarizing current injections and selectively reduced the slow component of the spike after-hyperpolarization (AHP). omega-Conotoxin decreased both the rising and falling slopes of the normal action potential, reduced the peak amplitude of the spike AHP, and, in some of the neurones, reduced the ISI during depolarization. The Na+ spikes recorded in Ca(2+)-free medium were not altered by omega-conotoxin. 4. The SOP was not blocked by octanol (100-200 microM), amiloride (100-250 microM), or Ni2+ (100-300 microM). However, at 500 microM Ni2+ attenuated the SOP. 5. Application of apamin (0.5-2.0 microM) induced irregular firing or bursting, abolished the slow component of the spike AHP and reduced its peak amplitude. In the presence of TTX and apamin long-duration plateau…
Read the paper
Related studies
- eggNOG 5.0: a hierarchical, functionally and phylogenetically annotated orthology resource based on 5090 organisms and 2502 viruses
- Online Survival Analysis Software to Assess the Prognostic Value of Biomarkers Using Transcriptomic Data in Non-Small-Cell Lung Cancer
- OptiType: precision HLA typing from next-generation sequencing data
- Nicotinic Cholinergic System and COVID-19: In Silico Identification of an Interaction between SARS-CoV-2 and Nicotinic Receptors with Potential Therapeutic Targeting Implications
- Saccharomyces cerevisiae cells have three Omega class glutathione S-transferases acting as 1-Cys thiol transferases
- Hemolysis at low blood flow rates: in-vitro and in-silico evaluation of a centrifugal blood pump
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.