Figure 2.

Cx46, but not Cx50, mediated intercellular transfer of cAMP. (A) Data from a Cx46 cell pair with a gap junctional conductance of 31 nS are shown. The SpIH current recorded from cell 1 over time, in response to voltage pulses of 0 to 100 mV, returning to a tail potential of +50 mV. At time 0, the patch in cell 2 was opened initiating cAMP delivery. The SpIH tail current over time increased approximately 4-fold. (B) Cx50 failed to mediate transfer of cAMP. The SpIH current remained constant in the recipient cell after 500μM cAMP was released in the source cell. This Cx50 cell pair had a gap junctional conductance of 16 nS. (C) Expanded SpIH currents from when the whole cell patch was first opened (black asterisk/trace), and 280 seconds later (red asterisk/trace). The Cx46 cell pair showed an approximately 4-fold increase in SpIH tail currents. For the Cx50 cell pair, the SpIH tail currents were of the same magnitude, indicating little, or no, intercellular cAMP transfer through Cx50 channels. Data from a Cx43 cell pair with a conductance of 6 nS are shown for comparison.