Fig. 6.

R-568 produces similar inhibitory effects on I_sc in the colon at 1.25 mM extracellular ionized calcium (Ca_o²⁺). Rat distal colons were treated the same way by forskolin and R-568 as in the legend of Fig. 5 except that Ca_o²⁺ of 1.25 mM was used. A: I_sc responses to forskolin and R-568 in the absence of TTX. B: I_sc responses to forskolin and R-568 in the presence of TTX. C summarizes the ΔI_sc induced by R-568 in the absence and presence of TTX.