The in vitro sensitivity of erythrocyte aggregation to quinine: assessment by a serial blood sedimentation procedure.

A serial erythrocyte sedimentation procedure is based on maintaining blood in vitro in thermal (body temperature) and flow equilibrium, as changes in sedimentation rate are evaluated at 20-mm intervals. Each measurement was made 1 h after the determination was begun. We thus confirmed in vitro the clinically observed effects of quinine on blood cell aggregation. A delayed effect of quinine on aggregation corresponded to in vivo observations that aggregation is first affected 3 to 12 h after the drug is administered. Quinine’s greatest effect (p <0.01) on erythrocyte sedimentation in vitro was at 200 mm with 2 mg of quinine per 100ml of blood, 220 mm with 1 mg/100 ml, and 240mm with 0.5 mg/lOU ml.