The effects of indomethacin on systemic hemodynamics and blood flow in the conscious dog

Systemic hemodynamics and blood flow were measured in conscious beagle dogs treated with the nonsteroidal antiinflammatory agent indomethacin. Twenty minutes after 2 mg/kg of indomethacin i.v., mean arterial blood pressure increased 5%, but cardiac output fell 24%, due to a decline in heart rate (-10%) and stroke volume (-18%). Small nonsignificant reductions in total bone, coronary, spleen, renal, and brain blood flow paralleled this fall in cardiac output. Larger, statistically significant reductions in arterial perfusion were seen in the skin (-30%), stomach (-47%), and small intestine (-27%). The corresponding 83, 101, and 38% increases in vascular resistance in these tissue beds largely accounted for the 41% increase in total peripheral resistance with indomethacin. Vascular resistance increased slightly in the vehicle control group due to reduced skeletal muscle blood flow seen in both treatment groups. Ovarian and thyroid blood flow also decreased with indomethacin. Indomethacin thus exerts a relatively specific vasoconstriction in the skin and upper gastrointestinal tract of the conscious dog.