Angiotensin II effects on platelet function.
The effects of angiotensin II (ANG II) alone and in combination with other agonists on platelet aggregation, thromboxane B2 (TxB2) synthesis and cytosolic [Ca2+]i were investigated. Angiotensin II (10(-11)-10(-7) mol/l) alone had no direct effect on aggregation, TxB2 production or [Ca2+]i after short- (< 2 min) or long-term (30 min) incubation. In contrast, low concentrations of ANG II (10(-11) mol/l) enhanced adrenaline-induced platelet aggregation but high concentrations (10(-7) mol/l) had an inhibitory effect. Moreover, ANG II (10(-11)-10(-7) mol/l) augmented platelet responses to the TxA2 mimetic U44069. The facilitatory effect of ANG II on adrenaline-induced platelet aggregation was abolished by pretreatment of platelets with flurbiprofen. Thromboxane B2 synthesis by adrenaline-treated platelets was inhibited by ANG II. The results indicate that ANG II stimulation of agonist-induced platelet activation is due to potentiation of the effects rather than the synthesis of TxA2.
Ding
Y A
YA
MRC Blood Pressure Unit, Western Infirmary, Glasgow, Scotland.
MacIntyre
D E
DE
Kenyon
C J
CJ
Semple
P F
PF
D000804:Angiotensin II / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects*; D002118:Calcium / Q000097:blood; D006801:Humans; D066298:In Vitro Techniques; D015539:Platelet Activation / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects; D010979:Platelet Function Tests; D013929:Thromboxane B2 / Q000096:biosynthesis / Q000097:blood
D000804:Angiotensin II; D013929:Thromboxane B2; D002118:Calcium