Figure 3. Effect of acetylcholine alone (closed square) or with the nitric oxide synthase inhibitors, n-methyl-l-arginine (open circle) or 7-nitroindazole (closed circle), the nitric oxide scavenger, hemoglobin (inverted closed triangle), or the guanylate cyclase inhibitor, methylene blue (open triangle) on detector aortic vascular ring tension after perfusion through spinal cord slices. Values expressed as mean+/- SE percent maximum relaxation of 7-11 rings. *Acetylcholine curve differs from each antagonist treatment by two-way analysis of variance (P < 0.05).