Novel devices for the predictable delivery of nitric oxide to aqueous solutions

Nitric oxide (NO), a recently discovered biological molecule synthesized by many cells, has many physiological roles including blood pressure regulation, neurotransmission, and inhibition of platelet adhesion. However, NO and reactive species formed in the presence of oxygen and superoxide can also be cytotoxic, mutagenic, or carcinogenic. Two novel devices were developed to deliver controlled and predictable amounts of NO to aqueous solutions for studying the effects of NO on biological systems. The devices contained either a slit or a tube composed of a gas-permeable membrane. Aqueous solution flowed on one side of the membrane while the other side of the membrane was exposed to NO gas. Mathematical models were used to predict the bulk or mixing-cup NO concentration in the aqueous solution at the exit of each delivery device following exposure to NO gas. Model predictions were in good agreement with experimental values at both 25 and 37 degreesC. One of the delivery devices was also connected to a well-stirred and oxygenated chamber. Model predictions of the chamber NO concentration, which included the reaction of NO with O2, were in excellent agreement with experiments.