Influence of prostacyclin on distribution of canine femoral blood flow

Prostacyclin (PGI₂) has been used clinically in the treatment of ischemic peripheral vascular disease. While intravenous infusions have been reported to be beneficial, the preferred route of administration (intravenous or intraarterial) and the influence of PGI₂ on distribution of femoral blood flow have yet to be established. Bilateral femoral arterial blood flow was measured electromagnetically in 10 anesthetized adult mongrel dogs. The distribution of femoral arterial blood flow (FAQ) to skin, muscle, bone, and arteriovenous anastomoses (AVA) was determined by using femoral intraarterial injections of radioactively labeled microspheres before, during, and 30 min after 20-min intravenous (n = 5) and intraarterial (n = 5) infusions of PGI₂ at 0.1 μg kg^-1 min^-1. Control FAQ was 76 ± 15 (mean ± SEM) ml/min and its distribution to skin, muscle, bone, and AVA was 13 ± 3%, 43 ± 8%, 17 ± 4%, and 26 ± 7%, respectively. Arterial pressure was 127 ± 7 mm Hg. Intraarterial infusions of PGI₂ significantly (P < 0.05) increased FAQ to 240 ± 43 ml/min which was sustained throughout the infusion. Distribution of FAQ to skin increased significantly (P < 0.05) to 47 ± 8%, while that to the muscle of the thigh decreased to 17 ± 4% (P < 0.05). During intravenous infusion of PGI₂ at the same concentration, FAQ did not change significantly and its distribution remained unchanged; however, there was a significant (P < 0.05) reduction in arterial pressure to 78 ± 6 mm Hg. No significant changes occurred in cardiac output, pulmonary arterial pressure, arterial blood gases, paw or core body temperatures. These data demonstrate the superiority of intraarterial PGI₂ as a potent vasodilator in the canine hindlimb. The redistribution of FAQ to the skin during intraarterial infusion of the drug would have potentially valuable applications in the clinical treatment of ischemic peripheral vascular disease.