Figure 1.

Noxious electrical stimulation increased BP and hemorrhage after a lower thoracic contusion injury and this effect was blocked by a spinal transection. (A) Experimental design and timeline for experiment 1. (B) Sham-operated rats that received electrical stimulation (Shk) exhibited higher systolic blood pressure over the next 3 h (T0–T3). Transection surgery blocked this effect. (C) Rats treated with electrical stimulation exhibited higher heart rate over the 3 h. (D) Both transected groups and the sham-operated rats that received shock displayed a significant increase in tail blood flow. Sham-operated unshocked animals remained unchanged. (E) Quantification of peak absorbance at 420 nm (the wavelength associated with hemoglobin). Sham shocked rats showed a higher peak absorbance than unshocked rats. Transection surgery blocked this effect. (F) Quantification of hemoglobin content based on formation of cyanomethemoglobin (Drabkin’s assay). Tissue from sham shocked rats contained a higher concentration of hemoglobin relative to animals that had undergone a spinal transection. (G) Immunoblot quantification for hemoglobin showed that tissue samples from sham-operated rats that received shock had higher levels of hemoglobin relative to both the sham-operated unshocked group and both groups that received a transection. Asterisks indicate statistical significance (*p < 0.05, **p < 0.01, n = 8). An asterisk placed over a group indicates that the group differs from all the others. Error bars represent the standard error of the mean (SEM).