Fig. 7. Effects of GABA on the rates of fluid and protein secretion induced by electrical salivary duct nerve (SDN)-stimulation. (A) Experimental regime and fluid secretion induced by electrical SDN-stimulation in the absence (8 V, 0.2 ms stimuli applied at 10 Hz) and presence (8 V, 0.2 ms stimuli applied at 2 Hz) of GABA. 5 µmol l^–1 GABA increased the rate of fluid secretion induced by a low frequency of electrical stimuli. After GABA washout the gland was stimulated at a frequency of 10 Hz again to obtain a control for gland functionality. The open rectangle indicates the five saliva samples/time periods that served as control for the protein assay in C. The light gray rectangle labels the five saliva samples/time periods that served as a control for the comparison of the secretion rates in B. The dark gray rectangle indicates the saliva samples/time period when GABA was applied. Application times are indicated by horizontal bars. (B) 5 µmol l^–1 GABA increases the rate of fluid secretion 2.5-fold from 6.8±1.1 to 16.7±1.7 nl min^–1 (N=7, ^*P<0,0171). (C) 5 µmol l^–1 GABA increases the rate of protein secretion from 2.9±0.7 µg min^–1 4-fold to 12±3.8 µg min^–1 (N=7, ^*P=0.03).