Inducible nitric oxide synthase in uterine smooth muscle

The expression of inducible nitric oxide synthase (iNOS) mRNA in rat uterus upon in vivo stimulation with lipopolysaccharide (LPS) was studied by reverse transcription and polymerase chain reaction. The injection of LPS induced an increase in mRNA levels of a macrophage-type iNOS. In unstimulated rats, low levels of iNOS mRNA was detected in the uterus and lungs, but absent or negligible in the kidneys and liver. NO was produced in the LPS-treated uterus by addition of 1 to 1000 microM L-arginine. The production of NO in uterine tissue that faces the outside of the body may provide a bacteriocidal protective function against microorganisms in physiological condition. However, NO produced in a large amounts by cytokine and LPS may play some pathological reaction during septic shock or infection.