[Effects on hemodynamics and myocardial metabolism of prostaglandin E1 and trimethaphan after a descending aorta cross-clamp in experimentally coronary constricted dogs].

We investigated the hemodynamic effects of prostaglandin E1 (PGE1) and trimethaphan (TMP) during cross-clamp of the descending aorta in experimentally coronary constricted dogs. Using 21 mongrel dogs, the blood flow of the left anterior descending coronary artery was reduced to 50% by constricting the artery. After stabilization of hemodynamics, we cross-clamped descending aorta and administered PGE1 (1.0 microgram.kg-1.min-1) or TMP (5.0 micrograms.kg-1.min-1). The drugs were discontinued just before the clamp on the aorta was released. In the PGE1 group, cardiac output (CO) and left ventricular dp/dt (LVdp/dt) increased significantly 5 minutes after clamping, with CO remaining at its high level even after the clamp was released. In the TMP group, CO increased significantly 15 minutes after administration and returned to the preclamping value soon after declamping. LVdp/dt was unchanged during clamping and decreased significantly after declamping. In addition, marked increase of the myocardial blood flow (MBF) in the ischemic areas was seen in the PGE1 group, whereas no changes were seen with the TMP. In the ischemic heart, PGE1 can not only decrease afterload which is elevated by the cross-clamping of the aorta, but also increase the coronary blood flow and MBF in the ischemic areas.