Page 94 - YORAM RUDY BOOK FINAL

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Figure 3.14. Experiment showing role of I Ca,L in conduction across expansion site. Experiments
were conducted in patterned cell cultures of neonatal rate myocytes. Top panels: antegrade
conduction from a narrow strand across abrupt expansion into a large bulk area. Bottom panels:
retrograde conduction from the large area into the narrow strand. A. Diagram of the cell culture;
dots represent recording diodes. B. Optically recorded AP upstrokes from the narrow strand (thin
lines) and the bulk area (thick lines). A delay of ~2msec occurs during antegrade conduction in the
expansion region (top panel); the delay is absent during retrograde conduction (bottom panel).
C. Local superfusion with nifedipine (I Ca,L blocker) results in an antegrade conduction block
at the expansion (top panel) while retrograde conduction is unaffected (bottom panel).
This demonstrates that I Ca,L is necessary for successful conduction across the expansion site.
Adapted from Rohr and Kucera [221] with permission from the authors and Elsevier.