[The diameter of arterial and venous abdominal vessels during acute and chronic administration of nitrates. A sonographic study].

Fourteen male patients with coronary heart disease were randomly assigned to treatment periods with isosorbide dinitrate (ISDN) 120 mg/day (6 X 20 mg) and placebo for 4 weeks each, according to a double-blind protocol with intraindividual cross-over. The luminal diameters of the superior mesenteric artery, the hepatic artery, the superior mesenteric vein and the portal vein were determined sonographically in the supine position on days 1, 14 and 28 of both treatment periods 90 min after drug intake. The measurements were repeated after 1.6 mg sublingual nitroglycerin. On day 1 of drug intake the vessel diameters increased significantly after ISDN as compared to placebo: superior mesenteric artery: +11%; hepatic artery: +26%; superior mesenteric vein: +17%; portal vein: +11% (p less than 0.05). No differences in luminal diameters between both drug regimens were found on days 14 and 28. Additional nitroglycerin caused a marked diameter increase during the placebo period (14-21%; p less than 0.001) and on days 14 and 28 of ISDN therapy, while the drug effects were absent after maximal ISDN-induced vasodilatation on day 1. Thus, nitroglycerin and isosorbide dinitrate administered acutely caused a comparable vasodilatation of arterial and venous vessels in the splanchnic region. During sustained therapy with isosorbide dinitrate the vasodilatory effects of the drug were lost. It is supposed that a decrease of blood pooling in the splanchnic region occurs during sustained ISDN therapy. Despite this tolerance development to the circulatory effects of isosorbide dinitrate, nitroglycerin remained effective with regard to arterial and venous vasodilatation.