Classification of the serum lipoproteins of vertebrates is based on their density, flotation rate, or electrophoretic mobility.
Much attention has been given to human lipoproteins, since they may be involved in cardiovascular diseases. Because pig blood is available fresh and in large quantity and this omnivorous: animal has been used extensively in cardiovascular research (1) , electrophoretic and ultracentrifugal
(2) correlations were #made on pig serum lipoproteins.
In contrast to human serum there are only four major protein fractions in pig blood serum which can be detected electrophoretically in agar gel: albumin, az-, /3-, and y-globulins. Apparently a,-globulins are absent in pig serum (3). Ultracentrifugally, all main lipoprotein classes are present in pig blood serum. However the low-density lipoprotein usually has two peaks (2) and sometimes an additional, intermediate peak.
Electrophoresis of lipoproteins has been rather unsatisfactory. Paper media do not yield sticient resolution and agar may interact with lipoproteins (4). Newer materials like cellulose acetate (5, 6) or polyacrylamide gel (7, 8) have also been used. However the former media cannot be employed on a preparative scale and it was established in preliminary experiments that the major lipoprotein classes would not enter the latter media. The present study was done using agarose gel, which was found not to suffer from any of these disadvantages.