Medicinal Chemistry and Pharmacology, Research and Development Division, Smith Kline & French Laboratories, Philadelphia, Pennsylvania 19101. Received July 15, 1983'hi-and tetrapeptide analogues were synthesized and evaluated as renal vasodilators. These peptides were prepared by standard coupling reactions, which also provided good yields with hindered a-methyl amino acid derivatives. Preliminary evidence of renal vasodilator ...