6-keto-PGE1 exhibits more potent bronchodilatory activity in the cat than its precursor, PGI2.
Spannhake EW, Levin JL, Hyman AL, Kadowitz PJ. 6-keto-PGE1 exhibits more potent bronchodilatory activity in the cat than its precursor, PGI2. Prostaglandins. 1981 Feb; 21(2):267-75.