Uptake of hexakis(t-butylisonitrile) technetium (I) and hexakis(isopropylisonitrile) technetium (I) by neonatal rat myocytes and human erythrocytes.

The uptake mechanism of two potential cardiac imaging agents [99mTc]hexakis(t-butylisonitrile) technetium (I) (TBI) and [99mTc]hexakis(isopropylisonitrile) technetium (I) (IPI) has been studied using neonatal rat myocytes and human erythrocytes. Uptake of these complexes was rapid, of greater magnitude than seen previously for 42K, and was unaffected by either 0.15 mM ouabain or 10 mM KCI. Both [99mTc]isonitrile complexes had a high affinity for the membranes of the myocytes and erythrocytes. The data suggest that the uptake is not dependent on the membrane Na+/K+ ATPase but may be related to the lipophilicity of these agents as evidenced by the rapidity, tenacity, and quantity of the binding observed.