Figure 2. The effect of intrathecal 8-Br-cGMP (2.5 μm, 10 μl) and vehicle (PBS, 10 μl intrathecal) injected prior to haemorrhage (1.5% body weight) on MAP (mmHg ± S.E.M.) measured throughout the removal of blood.

MAP during haemorrhage is expressed as a percentage of the initial MAP. *, a significantly different MAP value at x ml blood (100 g body weight)⁻¹ (P < 0.05, Dunnett's post test), compared to the MAP value prior to the onset of haemorrhage; 0 ml blood (100 g body weight)⁻¹. MAP maintenance was observed in cGMP-treated rats till 1.35 ml blood (100 g body weight)⁻¹ had been removed as opposed to maintenance of MAP till 0.90 ml blood (100 g body weight)⁻¹ was removed in the control group. The lines of regression formed by the decrease of MAP over the course of haemorrhage are statistically different (P < 0.01); the control group exhibits a steeper gradient than the group treated with cGMP.