Fig. 2.

Uroguanylin stimulates cGMP accumulation only in pregnant guinea pig myometrium. A and B, cGMP elevation was stimulated by uGN in a dose-dependent fashion and was insensitive to the addition of 10 μM ODQ in pregnant myometrium (A), but not nonpregnant myometrium (B). Addition of 2Cl-ATP (1 μM) or isatin (10 μM) prevented cGMP accumulation to 100 nM uGN. Data are mean ± S.E.M. from two replicate tissues from six nonpregnant and four-six pregnant animals (50–60 days gestation). *, p < 0.05; ***, p < 0.001; ns, nonsignificant compared with control. C, particulate GC-C activity was measured in vitro in the myometrial homogenate from four pregnant animals (50–60 days) after the addition of uGN in the presence and absence of putative GC inhibitors. Data are mean ± S.E.M. from three experiments performed in triplicate.