Change in vascular cAMP and cGMP contents in portal hypertensive rats

The purpose of this study was to investigate the possible changes of cyclic nucleotide contents in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation (PVL) in Sprague-Dawley rats. Sham-operated rats served as controls. Hemodynamic and cyclic nucleotide measurements were performed at 14 days after surgery. The portal venous pressure was significantly higher, while systemic arterial pressure and heart rate were lower in PVL rats than those in controls. Basal cAMP (PVL, 10.91 +/- 0.98, vs. sham, 8.08 +/- 0.81 pmol/mg protein) and cGMP (PVL, 0.91 +/- 0.12, vs. sham, 0.59 +/- 0.05 pmol/mg protein) contents in the tail artery were significantly higher in PVL rats. Isobutyryl methylxanthine (10(-5) M), a nonspecific phosphodiesterase inhibitor, exerted similarly stimulating effects on the tissue cGMP (PVL, 158 +/- 10, vs. sham, 178 +/- 20%) and cGMP (295 +/- 28 vs. 316 +/- 71%) levels in both PVL and control rats; so did forskolin (10(-6) M) on the cAMP (184 +/- 20 vs. 197 +/- 66%) content in both groups. Our results showed that the arterial cAMP and cGMP contents were higher in PVL rats, which may contribute to the reduction of peripheral resistance in portal hypertension.