Photodynamic damage induced by bilirubin on human platelets: possible relevance to newborn pathology.
Several reports have appeared showing the possibility of bilirubin-sensitized photodamage. We have extended these observations to platelets. In the presence of 300 microM bilirubin the in vitro irradiation of isolated platelets or platelet-rich plasmas with visible light induced significant lysis as determined by the release of lactate dehydrogenase (LDH). The extent of LDH release was a function of irradiation time, being about 20% after 2 h of irradiation. A loss membrane-bound ATPase activity was also observed at earlier times, indicating that membrane damage was preliminary to the lytic effect. The release of beta-thromboglobulin, induced by close cell-to-cell contact, was lower in bilirubin- and light-treated platelets with respect to controls. Our results suggest that bilirubin may act as a photodynamic agent producing some damage on human blood platelets.
D000251:Adenosine Triphosphatases / Q000009:adverse effects; D001663:Bilirubin / Q000494:pharmacology / Q000528:radiation effects*; D001792:Blood Platelets / Q000187:drug effects*; D006801:Humans; D007567:Jaundice, Neonatal / Q000628:therapy; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008027:Light / Q000009:adverse effects; D010789:Phototherapy / Q000009:adverse effects*; D013997:Time Factors
D007770:L-Lactate Dehydrogenase; D000251:Adenosine Triphosphatases; D001663:Bilirubin