r ox n~a- - n Per g>amon Tosl con, Vol . 32, No. B _ pp . _ 91925, 1994 ~114) t - 01~1( 94) E0035- 6 Ri med in Gt a®Bri t ai n Al l rich r caer ved 0041- 01ot i 9a rr . oo+o. ao BI OLOGI CAL PROPERTI ES OF THE VENOM OF THE PAPUAN BLACK SNAKE ( PSEUDECHI S PAPUANUS ) : PRESENCE OF A PHOSPHOLI PASE A z PLATELET I NHI BI TOR A . S. KAMI GUTI , 1 G . D . LAI xc, 2 G . M . LowE, l M . ZUZEL, 1 D . A . WARRELL 3 and R . D . G . TI - >EnxsTOx 2* ' Uni ver si t y Depart ment of Haemat ol ogy, Royal Li ver pool Hospi t al , Li ver pool , U .K .; 2 Venom Resear ch Uni t , Li ver pool School of Tr opi cal Medi ci ne, Pembr oke Pl ace, Li ver pool L3 SQA, U .K . ; and 3 Cent r e f or Tr opi cal Medi ci ne, Uni ver si t y of Oxf or d, John RadcGf f e Hospi t al , Oxf or d, U .K. ( Recei ved 3I Januar y 1994 ; accept ed 17 Mar ch 1994) A . S. KAMI GUTI , G . D . LAI NG, G . M . LowE, M . ZUZEL, D . A . WARRELL and R . D . G . Ti ->EAI CSTOx . Bi ol ogi cal pr oper t i es of t he venom of t he Papuan bl ack snake ( Pseudechi s papuanus) : pr esence of a phosphol i pase A 2 pl at el et i nhi bi t or . Toxi con 32, 91 X925, 1994 . - The whol e venom of Pseudechi s papuanus, in addi t i on to its ant i coagul ant act i vi t y, powerf ul l y i nhi bi t ed pl at el et aggr egat i on i nduced by ADP, adr enal i ne, col l agen, r i st ocet i n and t hrombi n . Hi gh l evel s of phosphol i pase A 2 ( PLA2 ) act i vi t y wer e det ect ed . A m ild pr ocoagul ant act i vi t y was al so obser ved . Fol l owi ng exposur e of pl at el et s to P . papuanus venom, pl at el et f act or 3 ( pr ocoagul ant pl at el et phosphol i pi d) showed decr eased cof act or act i vi t y in f act or X act i vat i on by Russel l ' s vi per , venom suggest i ng t hat t he venom PLA2 pl ays a maj or r ol e in t he i nhi bi t i on of t he coagul at i on mechani sm . In vi vo r odent assays conf i rmed t he i nhi bi t or y ef f ect on pl at el et s and t he haemor r hagi c and neur ot oxi c act i vi t i es . It is possi bl e t hat PLA2 is r esponsi bl e f or ant i coagul at i on and t hat t hi s, combi ned with t he ef f ect on pl at el et aggr egat i on, a m ild pr ocoagul ant and a moderat el y pot ent haemor - r hagi n, is r esponsi bl e f or t he haemor r hagi c di at hesi s obser ved in syst em i cal l y envenomed pat i ent s . Pol yval ent ( Aust r al i a- Papua New Gui nea) Common- weal t h Ser t un Labor at or i es ant i venom, cur r ent l y used f or cl i ni cal t reat ment of snakebi t e in Papua New Gui nea, pr oved hi ghl y ef f ect i ve agai nst P . papuanus venom in r odent and in vitro assays, despi t e t he absence of t hi s par t i cul ar venom f r om t he i mmuni si ng m i xt ur e . I NTRODUCTI ON THE PAPUAN bl ack snake, Pseudechi s papuanus, occur s al ong t he sout her n coast of New Gui nea . Twent y- f i ve year s ago it was t hought to be t he maj or cause of snakebi t e in t he Papuan r egi on ( CAMPBELL, 1967) , but mor e r ecent obser vat i ons suggest t hat it is now unc ommon ( LALLOO et al ., 1994) . In t he accompanyi ng paper ( LALLOO et al ., 1994) t he cl i ni cal and l abor at or y f eat ur es of ni ne cases of pr oven bi t es by P . papuanus ar e descr i bed, and t he l i t er at ur e on bi t es by t hi s speci es is c r i t i c al l y r evi ewed . Apar t f r omneur ot oxi c si gns, ' Aut hor to whom cor r espondence shoul d be addr essed. 915