Response of peripheral collateral arteries in the dog to prostaglandins E1, E2, F2 alpha, and I2 (prostacyclin).

Abstract

Prostaglandins (PG) E2, E2, E2 alpha, and I2 [prostacyclin (PGI2)] were tested in vitro on collateral arteries that enlarge following chronic occlusion of the femoral artery in the dog. After contraction with an ED50 dose of KCl, serial doses of a PG were added. Collateral arteries relaxed significantly to PGI2 (10(-7)--10(-5) M). Normal, similarly sized branch arteries did not relax. The contractile response of collateral arteries to PGE1, PGE2, and PGF2 alpha was qualitatively similar to that of branch arteries, but the magnitude of the responses for collateral arteries was PGF2 alpha = PGE2 greater than PGE1. The magnitude of the response for branch arteries was PGF2 alpha much greater than PGE2 greater than PGE1. The effects of the PGs on anterior tibial arteries from the contralateral limb and on anterior tibial arteries exposed to low pressure below the occlusion did not differ. Thus the lowered pressure in the limb with the occluded femoral artery was not responsible for differences in the effects of the PGs on collateral arteries. Collateral arteries are more sensitive to the relaxant effects of PGI2 in high doses and are less sensitive to the contractile effects of other PGs, particularly PGF2 alpha, than similarly sized arteries. This suggests that therapeutic doses of PGI2 may increase blood flow to ischemic areas.