The data on skeletal muscle metabolism published during the last 15 years contrasts with the lack of information on smooth muscle metobolism over this same period. Recently we have been studying the intermediary metabolism of nonhuman primate myometrium (Macaca mulatta and Macaca fasicularis) during pregnancy and the follicular and luteal phases of an induced and a natural menstrual cycle. The overall goal of our studies on this smooth muscle is to gain information on metabolic control mechanisms: interrelationships of carbohydrate, lipid and protein metabolism, and cyclic nucleotide metabolism. We have collected and stored (-200 degrees centigrade) myometrial samples from 24 cycling monkeys and 20 myometrial samples from spayed monkeys after the administration of estradiol or estradiol plus progesterone. The total activity and kinetics of the rate-limiting enzyme hexokinase will be studied in these myometrial samples and the sensitivity of this enzyme to various effector molecules such as ADP and citrate. The activity of the enzymes synthesizing and degrading the cyclic nucleotides will also be determined in the same preparations. Preliminary work indicates that guanylate cyclase is less active in luteal than in follicular myometrium. We also intend to measure the levels of prostaglandin E2 and F2alpha in the cycling myometrium. Levels of enzyme activity will be measured in samples of taenia coli to determine if the changes seen during the menstrual cycle are specific for myometrial smooth muscle. Plasma estradiol and progesterone levels in these animals will be correlated with changes in metabolism.