Drug therapy can slow or forestall that vulnerability. That's troubling, maintains physiologist Kent Hermsmeyer, who coauthored two of the studies, because heart disease kills three out of every four postmenopausal women.
Hormone therapy delivers estrogen to make up the shortfall that occurs with menopause.
The new studies suggest that this duo's heart benefits depend on the form of progesterone used. Hermsmeyer's team at the Oregon Regional Primate Research Center in Beaverton gave estrogen daily to 18 rhesus monkeys whose ovaries had been removed to simulate menopause. After 4 weeks, the researchers injected the animals with two chemicals released by blood platelets, simulating a heart attack. In monkeys receiving MPA and estrogen, this injection provoked an unrelenting constriction in the coronary artery, cutting off blood flow. Unless treated within minutes, the animals would have died, says Hermsmeyer.