Sampling Small Volumes of Saliva for Determination of the Stress Hormone α-Amylase: A Comparative Methodological Study

Salivary alpha amylase was taken into account as an important physiological indicator in psychoneuroendocrinological research focusing on stress. Two sampling devices that allow saliva collection through absorption to a cotton roll (Salivette-method) or to small cotton pellets (VectaSpin Micro [VSM]-method) were studied. Any loss of salivary alpha-amylase (sAA) activity in relation to the saliva volume absorbed and harvested by centrifugation was examined. A pooled saliva sample prepared from stimulated whole saliva (collected by drooling) of 30 subjects was used. Three different saliva volumes (2.9 ml, 1.5 ml, and 0.8 ml) were tested on cotton rolls and two (0.03 ml, and 0.015 ml) on cotton pellets. The sample sAA activity was determined from the hydrolysis of 2-chloro-4-nitrophenyl-α-D-maltotrioside. In comparison with the original drooling sample, no sAA loss was observed in 1.5 ml samples tested with Salivette, while a significant decrease of activity was recorded with smaller volumes. VSM collected samples showed a non-volume dependent decrease of sAA activity of about 25%. Salivette requires large saliva volumes to allow an accurate sAA estimation. With cases of limited saliva access, VSM may be a suitable sampling device.