HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Erdahl, W. L. Articles by Pfeiffer, D. R. Search for Related Content PubMed PubMed Citation Articles by Erdahl, W. L. Articles by Pfeiffer, D. R. Social Bookmarking                      What's this?

J Biol Chem, Vol. 275, Issue 10, 7071-7079, March 10, 2000

Ionomycin, a Carboxylic Acid Ionophore, Transports Pb²⁺ with High Selectivity^*

Warren L. Erdahl, Clifford J. Chapman, Richard W. Taylor^§, and Douglas R. Pfeiffer^¶

From the  Department of Medical Biochemistry, Ohio State University, Columbus, Ohio 43210 and the ^§ Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019

Studies utilizing phospholipid vesicle loaded with chelator/indicators for polyvalent cations show that ionomycin transports divalent cations with the selectivity sequence Pb²⁺ > Cd²⁺ > Zn²⁺ > Mn²⁺ > Ca²⁺ > Cu²⁺ > Co²⁺ > Ni²⁺ > Sr²⁺. The selectivity of this ionophore for Pb²⁺ is in contrast to that observed for A23178 and 4-BrA23187, which transport Pb²⁺ at efficiencies that are intermediate between those of other cations. When the selectivity difference of ionomycin for Pb²⁺ versus Ca²⁺ was calculated from relative rates of transport, with either cation present individually and all other conditions held constant, a value of ~450 was obtained. This rose to ~3200 when both cations were present and transported simultaneously. 1 µM Pb²⁺ inhibited the transport of 1 mM Ca²⁺ by ~50%, whereas the rate of Pb²⁺ transport approached a maximum at a concentration of 10 µM Pb²⁺ when 1 mM Ca²⁺ was also present. Plots of log rate versus log ionomycin or log Pb²⁺ concentration indicated that the transporting species is of 1:1 stoichiometry, ionophore to Pb²⁺, but that complexes containing an additional Pb²⁺ may occur. The species transporting Pb²⁺ may include H·IPb·OH, wherein ionomycin is ionized once and the presence of OH maintains charge neutrality. Ionomycin retained a high efficiency for Pb²⁺ transport in A20 B lymphoma cells loaded with Indo-1. Both Pb²⁺ entry and efflux were observed. Ionomycin should be considered primarily as an ionophore for Pb²⁺, rather than Ca²⁺, of possible value for the investigation and treatment of Pb²⁺ intoxication.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				S. A. Hamidinia, O. I. Shimelis, B. Tan, W. L. Erdahl, C. J. Chapman, G. D. Renkes, R. W. Taylor, and D. R. Pfeiffer Monensin Mediates a Rapid and Selective Transport of Pb2+. POSSIBLE APPLICATION OF MONENSIN FOR THE TREATMENT OF Pb2+ INTOXICATION J. Biol. Chem., October 4, 2002; 277(41): 38111 - 38120. [Abstract] [Full Text] [PDF]

				N. Hail Jr. and R. Lotan Examining the Role of Mitochondrial Respiration in Vanilloid-Induced Apoptosis J Natl Cancer Inst, September 4, 2002; 94(17): 1281 - 1292. [Abstract] [Full Text] [PDF]