BIIB 513 and
EMD 85131 are selective inhibitors of the Na+/H+ exchanger-1 (NHE-1) that are benzoylguanidine derivatives of the clinically employed
diuretic amiloride. Prior studies have suggested a role for NHE-1 activity in platelet activation and aggregation using
amiloride or its non- benzoylguanidines derivatives. However, the concentrations employed in these prior studies were at levels known to exert effects on other ion transport systems besides the NHE-1. Therefore, the purpose of this study was to examine the effects of more selective NHE-1 inhibitors,
BIIB 513 and
EMD 85131, on platelet aggregation and in vivo cyclic flow following arterial injury.
BIIB 513 and
EMD 85131 effects on ex vivo canine and human platelet aggregation in response to various agents was monitored via platelet aggregation. For analysis of in vivo
thrombus formation, a femoral artery
crush injury model was employed and a flow meter was used to monitor the effect of
BIIB 513 on cyclic blood flow. Treatment of either canine or human platelets with up to 1 mM of
BIIB 513 had no effect on aggregation induced by
platelet activating factor (PAF),
thrombin receptor activator peptide (TRAP), or
adenosine diphosphate (
ADP). Additionally, the structurally related compound
EMD 85131 at up to 1 mM failed to inhibit TRAP induced platelet aggregation. In vivo administration of up to 9 mg/kg of
BIIB 513 intravenously failed to affect cyclic flow in a canine model of femoral artery injury. These data demonstrate that the specific and selective NHE-1 inhibitors
BIIB 513 or
EMD 85131 have no effect on ex vivo platelet aggregation or in vivo cyclic flow following arterial injury.