Influence of primary prostaglandins on isolated canine renal arteries and veins.

The sensitivity and contractility of isolated canine renal arteries (RA) and renal veins (RV) to primary prostaglandin compounds (PG) was studied. Studies were also undertaken to determine whether specific receptors for PGs exist in RA and RV. RA and RV exhibited potent concentration-dependent contractile responses to all the primary PGs studied, including PGA1, PGA2, PGB2, PGD2, PGE1, PGE2, PGF1 alpha and PGF2 alpha. The contractile sensitivity (based on EC50's) of canine RA to PGs was: PGB2 greater than PGB1 approximately equal to PGE2 greater than PGF2 alpha approximately equal to PGA2 approximately equal to PGD2 approximately equal to PGA1 greater than PGF1 alpha greater than PGE1, whereas for RV it was: PGB2 greater than PGB1 approximately equal to PGD2 approximately equal to PGF2 alpha greater than PGA2 approximately equal to PGA1 greater than PGE2 much much greater than PGF1 alpha approximately equal to PGE1. In terms of the ability to generate a maximum contractile response on RA, PGB2 was the most potent and PGD2 the least potent, whereas for RV PGF2 alpha and PGB2 was the most potent and PGF1 alpha and PGE1 the least potent. Canine RA failed to elicit any consistent relaxant responses to PGE1, PGE2, PGA1, and PGA2. Renal veins, however, in which tone was induced by either PGs or serotonin responded with concentration-related relaxations to PGE1; other primary PGs did not induce relaxations on isolated RV. Use of specific pharmacologic antagonists (for catecholamines, serotonin, acetylcholine and histamine) failed to interfere with any of the PG responses. The data indicate that RA and RV: a) can exhibit differential responses to primary PGs; b) exhibit structure-activity relationships for the contractile action of PGs; and c) appear to have specific receptors for primary PGs which primarily subserve contraction.