Effects of prostaglandins and several vasoactive substances on blood pressure, respiration and blood flow by intra-ventricular, intra-arterial and intravenous routes.

Differences by routes of administration of the effects of prostaglandins and vasoactive substances on blood pressure, peripheral blood flow and respiration were investigated. Intravenous prostaglandins evoked respiratory excitation in rabbits, and lowered blood pressure more prominently and longer after intracarotid injection than after the intrajugular administration. The effects of prostaglandins were apparently more conspicuous after vertebral artery than via carotid artery. In rats, 1 microgram/kg i.v. of PGE1 and PGE2 caused a fall of blood pressure but 1 microgram/kg i.v. of PGF2 alpha caused a rise. PGF2 alpha produce a decrease of blood pressure when injected 10 micrograms/kg i.v.. A remarkable elevation of blood pressure occurred in rats following injection into the lateral cerebral ventricle of 0.1 microgram/kg of PGE1 or PGF2 alpha or of the same dose of 5-hydroxytryptamine (5-HT). Intra-arterial injection of PGE1 gave rise to an increase in blood flow of rabbit dorsal skeletal muscle whereas that of PGF2 alpha resulted in blood flows. The above results indicate that the effects of prostaglandins on these parameters essentially vary to slight extents with the species of animals and differ in intensity with routes of administration.