Influence of local anaesthetics on the aggregation and deformability of erythrocytes.

The effects of two local anaesthetics, procain and tetracaine, on erythrocyte aggregation and deformability under in vitro conditions are analysed. Fresh blood samples from healthy volunteers are obtained by venepuncture in test tubes containing heparin as anticoagulant. After centrifugation, plasma and cells are separated and buffy coat is discarded. The erythrocyte suspensions for aggregation and deformability measurement are prepared at hematocrit 34 and at 8% in buffered medium containing glucose and albumin, respectively. A part of the suspending medium in these samples is replaced by an equal volume of anaesthetic solution to obtain its final concentration ranging from 0.001 to 1 g/l. The results show that with the increase of anaesthetic concentration the deformability index and the aggregation index are reduced. The change in erythrocyte shape may contribute to the decrease in aggregation. The combined effect of these parameters may affect blood flow under varied experimental conditions.