Influence of local anaesthetics on the aggregation and deformability of erythrocytes

The effects of two local anaesthetics, procain and tetracaine, on erythrocy te aggregation and deformability under in vitro conditions are analysed. Fr esh blood samples from healthy volunteers are obtained by venepuncture in t est tubes containing heparin as anticoagulant. After centrifugation, plasma and cells are separated and buffy coat is discarded. The erythrocyte suspe nsions for aggregation and deformability measurement are prepared at hemato crit 34 and at 8% in buffered medium containing glucose and albumin, respec tively. A part of the suspending medium in these samples is replaced by an equal volume of anaesthetic solution to obtain its final concentration rang ing from 0.001 to 1 g/l. The results show that with the increase of anaesth etic concentration the deformability index and the aggregation index are re duced. The change in erythrocyte shape may contribute to the decrease in ag gregation. The combined effect of these parameters may affect blood flow un der varied experimental conditions.