Nitric Oxide Inhibits Preterm Labor in the Rhesus Monkey

Abstract

Progression of mammalian pregnancy requires relaxation of uterine smooth muscle until parturition, but the mechanism that maintains uterine relaxation during pregnancy is unknown. Nitric oxide (NO) is a free radical with a variety of physiologic functions including smooth muscle relaxation. We hypothesized that NO may relax uterine smooth muscle and inhibit preterm labor. In chronically catheterized rhesus monkeys, NO administered as S-nitroso-N-acetylpenicillamine (SNAP) ablated the uterine electromyographic and mechanical contraction components of established preterm labor. These preliminary studies suggest that NO may be important in maintaining uterine quiescence during pregnancy, and exogenous NO may be useful in controlling preterm labor.

Key Words:

• Nitric oxide
• Tocolysis
• Fetal surgery