Fig. 8.

Vasopressin causes spike-like increases in intracellular Ca²⁺; BAPTA and W-7 block Akt activation. A: 1 nM AVP strikingly induced aperiodic spike-like increases in intracellular Ca²⁺ in microdissected IMCD cells, measured by Fluo-4 fluorescence [see also Supplementary Video (http://dir.nhlbi.nih.gov/papers/lkem/ca_spikes_video/)]. These increases occurred independently in each cell in an unsynchronized fashion throughout the IMCD. The signal intensities of selected cells (A and B) as a function of time (s) are represented below the images. Injection of vehicle did not alter frequency of Ca²⁺ spikes. B and C: IMCD suspensions were preincubated for 25 min in the absence or presence of 50 μM BAPTA (B) or 25 μM W-7 (C) and then incubated with vehicle or 1 nM dDAVP for 5 min. †Statistically significant vs. control. ‡Statistically significant vs. dDAVP alone.