Inhibition of nerve stimulation‐induced vasodilatation in corpora cavernosa of the pithed rat by blockade of nitric oxide synthase

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Abstract
1 The effect of inhibition of nitric oxide synthase by NG-nitro-l-arginine methyl ester (l-NAME) on nerve stimulation-induced vasodilatation in corpora cavernosa was studied in the pithed rat. Corporal vasodilatation was estimated by the increase in ratio (corpora cavernosal pressure/systemic blood pressure; CP/BP) following electrical stimulation of the sacral part of the spinal cord. 2 l-NAME (2, 5, 10 and 25 mg kg−1) caused an increase in BP and a dose-dependent inhibition of the rise in the CP/BP ratio following stimulation. 3 The inhibitory effect of l-NAME (25 mg kg−1) on the corporal response to spinal cord stimulation, as well as the pressor response, was partially prevented by prior administration of l- but not d-arginine (400 mg kg−1, i.v.). 4 l-NAME (20 mg kg−1, i.v.) did not inhibit the rise in corporal pressure resulting from direct intracavernosal administration of papaverine (400 μg over 2 min). However, this response was inhibited by 5-hydroxytryptamine (20 μg kg−1, i.v.). 5 The results are indicative of a role of nitric oxide (NO) in the corporal vasodilator response to erectile stimulation.