Table 1.

Resting and stimulated frequencies of amperometric events in various experimental conditions

ConditionControlCd2+K+Room temperature
Resting frequency (events/min)2.1  ± 0.6  (19)0.57  ± 0.20  (5)0.98  ± 0.40  (5)0.16  ± 0.10*  (5)
Stimulation frequency (events/min)7.2  ± 1.5  (39)0.40  ± 0.27*  (10)6.2  ± 2.0  (11)1.0  ± 0.3*  (10)
  • For each cell, amperometric events were counted during resting and stimulated periods. A typical sequence comprised 2 min of rest, one stimulation of 30 sec, a rest of 1.5 min, a second stimulation of 30 sec, and a final rest of 1.5 min. Control experiments refer to glutamate (300 μm) stimulation performed in normal saline at 32–35°C. Cd2+ experiments were performed in a saline supplemented with 50 μm Cd2+. K+experiments were performed with 100 mm K+ in the stimulation solution instead of glutamate. First row, Resting frequencies for each cell; numbers of cells in each condition are given in parentheses. Second row, Stimulated frequencies for each stimulation; total numbers of stimulations in each condition are given in parentheses. Values are means ± sem; *significantly different from control; t test; p < 0.05.

  • , Significantly different from resting frequency; pairedt test; p < 0.05. For each stimulation the stimulated frequency was compared with the resting frequency corresponding to the periods before and after this stimulation.