Figure 5.

Nitric oxide-stimulated cyclic GMP accumulation in non-labouring myometrium is blocked by GC inhibitors but not by scorpion toxin. Cys-No caused a 7.5 fold increase in basal cyclic GMP content (15.8±1.09 pmol mg protein⁻¹) in non-labouring tissues snap frozen during contractile experiments. OT (10 μM) alone (16.9±4.5 pmol mg protein⁻¹) had no effect on basal cyclic GMP content. Cys-NO (30 μM) stimulation of ODQ pretreated tissues (15 min, 1 μM) led to near complete inhibition of Cys-NO stimulation of cyclic GMP accumulation (P<0.001) and thus no significant elevation of cyclic GMP content over baseline (Basal vs Cys-NO with ODQ, P>0.05). Cys-NO stimulated cyclic GMP accumulation was not altered by IBTx (100 nM) treatment, which also did not alter the ability of ODQ and MB to block guanylyl cyclase. Data expressed as pmol of cyclic GMP mg protein⁻¹ are mean±s.e.mean, n=12).