Neutralization of UFH (a) and LMWH (b) in vivo (in rat model) by HBSPCM and protamine. Rats were injected with 25 U of UFH or LMWH and blood was collected after at 5 min post injection. HBSPCM (20 mg/Kg) or protamine (3 mg/Kg) was injected at 7 min, and blood was collected at different time points and analyzed for fXa levels.