Prostaglandins in diagnostic and therapeutic superior mesenteric artery pharmacoangiography

The hemodynamic effects of prostaglandins PGA1, PGE1, PGE2, and PGF2 alpha on the splanchnic circulation were evaluated in five chronic dogs with portal hypertension, periportal fibrosis, and portosystemic venous shunting. The maximum effect was achieved with dosages of 2 micrograms/kg/min after bolus injection into the superior mesenteric artery. With this dosage a monophasic increase of portal blood flow and pressure was found with PGA1, PGE1, and PGE2, whereas PGF2 alpha caused a biphasic response: an initial decrease in portal blood flow and pressure was followed by an increase in these parameters. The average peak increase in portal blood flow and pressure was similar for PGE1 and PGF2 alpha, and significantly smaller for PGA1 and PGE2. Average peak iodine concentrations in the portal blood after superior mesenteric angiography were highest with PGF2 alpha, similar for PGE1 and tolazoline, and lowest in controls. The vasoconstrictor effect of PGF2 alpha is, overall, reduced and less reproducible when compared with vasopressin. This investigation suggests that both PGE1 and PGF2 alpha are effective for improved arterial portography, the latter agent appearing superior. On the other hand, PGF2 alpha cannot be recommended as a therapeutic agent for the treatment for gastrointestinal and particularly variceal bleeding.