Figure 4. Examples of agonist-induced whole-cell currents at a concentration range that covers saturating responses.
Aa and Ba, original traces of currents induced by DMPP, ACh, nicotine and cytisine in 2 different cells (A and B). Pairs of indicated agonists were tested in cells voltage clamped at -70 mV using the perforated patch technique as described in Methods. Agonists were applied at concentrations indicated in Ab and Bb. Ab and Bb, dose-response relationship of peak currents constructed from the original recordings shown in Aa and Ba. Data points are mean peak currents measured in duplicate (□, ACh; ▵, DMPP; ○, nicotine; ▿, cytisine). Curves fitted to data points by means of eqn (1) revealed EC50 values of 19.7 μM for DMPP, 96.4 μM for ACh, 28.5 μM for nicotine and 22.2 μM for cytisine. A summary of related experiments is provided in Table 1A.