analysis of dv ( d ) /dtmax at various ca2+ concentrations , in the presence of nonpermeant divalent cations ( co2+ , mn2+ , and mg2+ ) , shown that these cations bind competitively at the same receptor site with differing dissociation constants , for all of these divalent cations , the order of binding would be co2+ greater than mn2+ greater than ca2+ greater than sr2+ , mg2+ .
C0007447
cations
C0007448
divalent cations