Functional antagonism by monoclonal antibody to digoxin in the guinea-pig atria

Abstract

A monoclonal antibody with a high affinity for digoxin (K a = 1.14 × 10 9 M) was produced by somatic cell fusion. This antibody, designated 35 6.1 , displayed little or no cross reactivity with other steroids. In the guinea-pig atria, 35 6.1 antagonized functionally the positive inotropic effect of digoxin but did not alter that of isoproterenol. Our results suggest that this monoclonal antibody may represent a useful probe for studying the physiological role of the putative endogenous digoxin-like factor in various pathophysiological conditions.