Abstract: Abnormalitites in the distribution of a dopamine D.sub.2 receptors in humans and other mammals are detected by(1) administering to a human or other mammal an amount of a .sup.18 F-radiolabelled compound sufficient to be detected by a positron emission sensitive means for imaging, said compound having affinity for said receptors selected from the group consisting of optically active or racemic compounds represented by the general formula: ##STR1## (2) forming at least one image showing the distribution of the radiolabelled compound within the human or other mammal using a positron emission-sensitive means for imaging; and(3) determining normality of the concentrations or distribution by comparing the image with an image showing the normal concentrations and distribution of the receptors in humans or mammals of the same species wherein R1-R4, n and m- are as set forth in the specification.

Abstract: A method for inducing an anticurare response by administering 2,4-diaminopyridine to a mammal is disclosed, together with pharmaceutical compositions containing an effective amount of 2,4-diaminopyridine either alone or in combination with an anticholinesterase agent. 2,4-Diaminopyridine is an antagonist of muscle relaxants used in anesthesiology and can increase neuromuscular transmission in certain disease states.