Cholesterol esterase stimulation by luteinizing hormone in luteinized rat ovaries.

Cholesterol esterase activity was measured in luteinized ovarian tissue from immature superovulated rats. Enzyme activity was determined from the rate of appearance of lmitic acid-l-14C, hydrolyzed from a cholesteryl pa lmitate-l-14C substrate during 30 min of incubation at 37 C. Direct proportionality of incubation time with hydrolysis and enzyme concentration with reaction velocity was established for the enzyme assay system. Esterase activity was present in all subcellular fractions but most enzyme activity was found in the 100,000 ×g defatted supernatant fraction. LH 10 ng), administered iv 1 hr before sacrifice, resulted in a highly significant (p <.001) increase esterase activity over saline-injected controls. suspension of 1500 ×g pellet from homogenized luteal tissue was incubated in the presence of ATP (1.7×10-3M), theophylline (10-3M) and LH or saline; the supernatant fractions from these incubations when added to the usual 100,000 ×g supernatant fraction produced no differences in esterase acti...