Modified paper chromatographic method for assay of myocardial depressant factor

A simplified paper chromatographic technique for assaying myocardial depressant factor (MDF) is presented. In addition to a serine standard, deproteinized plasma samples from rabbits subjected to hemorrhagic shock were applied to paper and chromatographed. The spot in the chromatograms occurring at a migration distance of 1.6 to 1.8 times that of the standard (RS = 1.6-1.8) was found by bioassay to contain the MDF. The chromatographic spots were developed with ninhydrin and eluted with 3 ml of 1% NaHCO3. The absorbance at 570 nm (A570) of each eluate was measured and compared against the A570 value of the eluted serine standard. A direct linear relationship was shown between MDF chromatographic and bioassay values for each animal. This technique for paper chromatographic assay of MDF is as sensitive, specific, and reliable as bioassay, but offers clear advantages of small sample volume requirement, reduced analysis time, and ease of performance with routinely available laboratory equipment.