These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Comparative action of methylmercury and divalent inorganic mercury on nerve terminal and intraterminal mitochondrial membrane potentials.
    Author: Hare MF, Atchison WD.
    Journal: J Pharmacol Exp Ther; 1992 Apr; 261(1):166-72. PubMed ID: 1560362.
    Abstract:
    Both methylmercury (MeHg) and inorganic divalent mercury (Hg++) alter the flux of ions and small molecules across nerve terminal membranes by mechanisms that may involve membrane depolarization. We compared the effects of MeHg and Hg++ on plasma (psi p) and mitochondrial membrane potentials (psi m) in synaptosomes using the potentiometric carbocyanine dye 3,3'-diethylthiadicarbocyanine iodide [diS-C2(5)]. Both mercurials (1-20 microM) produced concentration-dependent increases in dye fluorescence after 5 min of exposure which were not altered by removal of Ca++ from the medium. To determine directly effects of mercurials on psi p, predepolarization of psi m using NaN3 and oligomycin was necessary. Under this condition, MeHg- and Hg(++)-induced increases in fluorescence were associated with depolarization of psi p. A second approach was used to assess changes in psi p. In synaptosomes, the magnitude of the increase in fluorescence resulting from depolarization of psi p with a stimulus of constant intensity is a function of the resting psi p. The fluorescence response to depolarization of synaptosomes previously exposed to either MeHg or Hg++ (1-20 microM each) was reduced in a concentration-dependent manner relative to mercury-free controls. The concentration-dependent depolarization of psi p calculated in this manner correlated (r = 0.958) with calculations of psi p using direct measurements of increases in fluorescence intensity. MeHg- and Hg(++)-induced depolarizations were not altered by lowering Na+e or by the addition of the Na+ and Ca++ channel blockers tetrodotoxin and Co++, respectively. Thus, the effects of these two neurotoxic mercurials on synaptosomal membrane potentials were similar with respect to their loci but differed in magnitude.(ABSTRACT TRUNCATED AT 250 WORDS)
    [Abstract] [Full Text] [Related] [New Search]