The mechanism of coronary artery spasm has been hypothesized as follow
s: the dormant gene of the smooth muscle of the human coronary artery
is identical or similar to the active gene of the smooth muscle of duc
tus arteriosus, but can be activated by estrogen. The activation could
be preventable by progesterone. The prevention is due to the reductio
n of the number of estrogen receptors of the smooth muscle of the coro
nary artery.