NOVEL DEVICES FOR THE PREDICTABLE DELIVERY OF NITRIC-OXIDE TO AQUEOUS-SOLUTIONS

Nitric oxide (NO), a recently discovered biological molecule synthesiz ed by many cells, has many physiological roles including blood pressur e 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 nove l devices were developed to deliver controlled and predictable amounts of NO to aqueous solutions for studying the effects of NO on biologic al systems. The devices contained either a slit or a tube composed of a gas-permeable membrane. Aqueous solution flowed on one side of the m embrane while the other side of the membrane was exposed to NO gas. Ma thematical models were used to predict the bulk or mixing-cup NO conce ntration in the aqueous solution at the exit of each delivery device f ollowing exposure to NO gas. Model predictions were in good agreement with experimental values at both 25 and 37 degrees C. One of the deliv ery devices was also connected to a well-stirred and oxygenated chambe r. Model predictions of the chamber NO concentration, which included t he reaction of NO with O-2, were in excellent agreement with experimen ts.