6 ▁to ▁P AR - 1 ▁causes ▁a ▁conform ational ▁change ▁in ▁the ▁G PI I b / III a ▁re cept ors ▁on ▁plate lets , ▁giving ▁them ▁high ▁aff inity ▁for ▁f ibr in ogen . ▁F ibr in ogen ▁then ▁bind s ▁to ▁the ▁re cept ors , ▁cross link ing ▁several ▁plate lets ▁and ▁causing ▁aggreg ation . ▁A ggreg ation ▁in ▁TR AP test ▁may ▁be ▁reduced ▁or ▁absent ▁in ▁Gl anz mann ' s ▁th rom bas then ia , ▁where ▁G PI I b / III a ▁re cept ors ▁are ▁few ▁or ▁absent , ▁or ▁if ▁the ▁patient ▁is ▁taking ▁a ▁G PI I b / III a ▁ant agon ist . ▁Tra pt est ▁has ▁only ▁minor ▁sens itivity ▁for ▁in hib ition ▁of ▁CO X 1 ▁and ▁AD P - re cept ors . ▁ ▁AS A ▁Re agent ▁Adding ▁AS A ▁( ac et yl sal icy lic ▁acid ) ▁re agent ▁to ▁a ▁blood ▁sample ▁reduces ▁the ▁aggreg ation ▁responses ▁in ▁AS PI test ▁and ▁COL test . ▁AS A ▁irre vers ibly ▁in hib its ▁CO X 1 ▁in ▁plate lets , ▁thereby ▁in hib iting ▁the ▁production ▁of ▁T X A 2 . ▁The ▁AS A ▁Re agent ▁is ▁used ▁as ▁a ▁quality ▁control ▁in ▁the ▁plate let ▁function ▁testing ▁with ▁Multi plate , ▁allowing ▁the ▁assess ment ▁of ▁ab normal ▁plate let ▁responses ▁in ▁AS PI test ▁and ▁COL test . ▁ ▁G PI I b / III