Hyposensitivity to nerve stimulation in portal hypertensive rats: role of nitric oxide

Portal hypertension goes along with vascular hyporeactivity, partly mediated by nitric oxide (NO). Interactions between the adrenergic nervous system and NO in portal hypertension are undetermined. We tested (1) whether superior mesenteric arterial beds of portal hypertensive rats have an altered sensitivity to periarterial nerve stimulation (PNS) and (2) the role of NO in modulating nerve‐stimulated responses. Vasopressor responses to PNS (Hz, 2–32) were similar in preparations of partial portal vein‐ligated (PVL, n = 12) and control (CON, n = 12) rats (60.0 ± 6.7 and 47.8 ± 6.1 cmH2O respectively) for 24 Hz (NS), but sensitivity of vessels of portal hypertensive animals displayed a significant right‐ward shift [Hz needed for 50% of maximal response (Hz50) being 15.5 ± 0.4 and 12.9 ± 0.6 for PVL and CON respectively, P