1. Rate of voltage clamp-induced depolarization of DVR endothelial layer with di-8-ANEPPS.
Rate of voltage clamp-induced depolarization of DVR endothelial layer with di-8-ANEPPS. A: stripped DVR endothelial monolayer held at −90 mV by voltage clamp was subjected to 3 successive depolarizations to −10 mV for 100 ms (above graph). Fluorescence was recorded at 5 kHz using a PMT. The graph shows data averaged by a factor of 10 (to 0.5 kHz) and calibrated (8.4% per 100 mV) to show change in membrane potential vs. time (n = 7 vessels, 4 rats). The −90- to −10-mV voltage-clamp depolarization of the cell-patched endothelial cell yields a corresponding change of 15 to 20 mV over 100 ms. The depolarization and repolarization are rapidly tracked by di-8-ANEPPS fluorescence. B: stripped DVR endothelial layers were held at −90 mV and depolarized to −10 mV for 1,000 ms (n = 13 vessels, 8 rats) as di-8-ANEPPS fluorescence was recorded by PMT (sampling, 5 kHz). Individual data records during the 1,000-ms pulse were fitted to single exponentials to yield a time constant for the responses (0.61 ± 0.12 s). C: time scale of normalized di-8-ANEPPS fluorescence near the start of the −90- to −10-mV pulse is expanded to show the rapid response recorded by di-8-ANEPPS recordings. The bar above the abscissa shows the region further expanded in D. D: region of C near the origin of the pulse is further expanded to show that the response to depolarization occurs without a discernible delay, i.e., within a millisecond.
Zhong Zhang et al. Am J Physiol Renal Physiol 2014;306:F751-F763
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