Figure 2.

Phenylephrine-induced contraction in intact portal vein smooth muscle. (A) Isometric tension was measured after treatment with or without DC3B for 48 h. Note that the contractile response of untreated smooth muscle was biphasic, consisting of a phasic transient followed by a tonic phase. DC3B treatment inhibited the tonic phase of contraction with little effect on the initial, transient phase. (B) Summary of the effect of DC3B on PE-induced contraction in intact portal vein smooth muscle. DC3B significantly inhibited the tonic phase of contraction. Amplitudes of contraction in each phase were normalized to maximal Ca²⁺-induced contraction as 100% after permeabilization with α-toxin. The maximal Ca²⁺-induced contractions were: control, 1.6 ± 0.21 mN (n = 26); DC3B = 1.1 ± 0.17 mN (n = 30). The difference between these values was not statistically significant (p = 0.08).