[Hypotheses on the validity of the radioimmunologic measurement of FT4].

In patients undergoing long-term thyroid hormone therapy with constant doses the results of FT4 concentrations measured by radioimmunoassay (FT4-AMERLEX) were compared with calculated FT4 values and related to total thyroxine, serum TBG levels, respectively T4/TBG, to control the validity of radioimmunologic FT4 measurements for clinical routine diagnostic purposes. Based on mathematical analyses on the interdependence of these values the following principles were confirmed: free thyroxine measurements are dependent on total thyroxine with a power of x to the exponent and on T4/TBG-ratio with an exponential function. The percentage of free thyroxine (FT4/TT4 ratio) is inversely and exponentially related to serum TBG concentrations.

[3H]adenosine binding to bovine coronary arteries and myocardium.

The characteristics of [3H]adenosine binding to bovine myocardial and coronary tissue were investigated using the microsomal fraction obtained by fractionated centrifugation. Binding experiments consisting of equilibrium, kinetic and competition studies were performed employing a filtration assay. The coronary microsomal fraction yielded two classes of binding sites with different affinities and binding capacities.