Molecular and Cellular Biochemistry

, Volume 149, Issue 1, pp 263–265

Interaction of heavy metal toxicants with brain constitutive nitric oxide synthase

  • Chandra K. Mittal
  • William B. Harrell
  • Chander S. Mehta
Article

DOI: 10.1007/BF01076586

Cite this article as:
Mittal, C.K., Harrell, W.B. & Mehta, C.S. Mol Cell Biochem (1995) 149: 263. doi:10.1007/BF01076586

Abstract

This study was designed to evaluate thein vitro effects of transition heavy metal cations on activity of constitutive isoform of nitric oxide synthase (cNOS) in rat brain. NOS activity was determined in the cytosolic fractions of rat cerebral hemispheres by conversion of3H-L-arginine to3H-L-citrulline. Different concentrations of mercury (Hg2+), nickel (Ni2+), manganese (Mn2+), zinc (Zn2+), cadmium (Cd2+), lead (Pb2+) and calcium (Ca2+) were tested on NOS activity. While all the cations caused inhibition, there were differences in the apparent inhibition constants (Ki) among the cations. With the exception of calcium ion no other cation required preincubation with the enzyme preparation. These results indicate that while calcium ion modulate cNOS activity at regulatory site(s), inhibitory influence of toxic heavy metal cations may be exerted on the catalytic site(s) either by direct binding to it or by interfering with the electron transfer during catalysis.

Key words

NO synthasetoxic metalssignal transductioncalcium

Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • Chandra K. Mittal
    • 1
  • William B. Harrell
    • 1
  • Chander S. Mehta
    • 1
  1. 1.Division of Pharmaceutical Sciences, College of Pharmacy and Health SciencesTexas Southern UniversityHoustonUSA