Inhibited serum phospholipase A2 activity in hyperbilirubinemia.
OBJECTIVE
Phospholipase A2 activity is reported to be related to the physiology of various disorders, and the activity is modified by deoxycholic acid.


METHODS
Serum phospholipase A2 activity was measured by counting the radioactivity of 14C-palmitic acid released from L-3-phosphatidylcholine (1-palmitoyl-2-14C-palmitoyl) in 40 patients with hyperbilirubinemia due to malignant neoplasms and benign cholestasis. Phospholipase A2 activity in serum from healthy subjects was also measured after incubation with 5-30 mg of bilirubin per dL or 0.1-5 mM of cholic acid for 60 min at 37 degrees C.


RESULTS
Serum phospholipase A2 activity was significantly lower in patients with hyperbilirubinemia. There were negative correlations between serum phospholipase A2 activity and concentration of total bilirubin (r = 0.668; P < 0.0001) or total bile acids (r = 0.423; P < 0.05) in patients with hyperbilirubinemia. In 12 patients who underwent percutaneous transhepatic biliary drainage, the low serum phospholipase A2 activity was reversed while bilirubin concentrations decreased. Incubation of sera from healthy subjects with more than 3 mM cholic acid significantly reduced phospholipase A2 activity (P < 0.01), whereas incubation with bilirubin had no effect.


CONCLUSIONS
Inhibition of serum phospholipase A2 activity in patients with hyperbilirubinemia may be caused by increased serum cholic acid concentration.
Miyashita
M
M
First Department of Surgery, Nippon Medical School, Tokyo, Japan.
Onda
M
M
Nomura
T
T
Matsutani
T
T
Tsuchiya
Y
Y
Sasajima
K
K
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001647:Bile Acids and Salts / Q000097:blood; D001663:Bilirubin / Q000097:blood; D002250:Carbon Radioisotopes; D019826:Cholic Acid / Q000097:blood; D005260:Female; D006801:Humans; D006932:Hyperbilirubinemia / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D010741:Phospholipases A / Q000097:blood*; D054467:Phospholipases A2
D001647:Bile Acids and Salts; D002250:Carbon Radioisotopes; D010741:Phospholipases A; D054467:Phospholipases A2; D019826:Cholic Acid; D001663:Bilirubin