= T. O'Kelly
{c}
<T. O'Kelly> is the first author of a 1993 study testing the role of <nitric oxide> in relaxation of the human <internal anal sphincter>. Isolated <muscle> strips were mounted in organ baths for measurement of tension at fixed length. Electrical stimulation evoked nerve-dependent relaxation, allowing the investigators to test which chemical pathway connected stimulation to the mechanical response.<Nerve mediated relaxation of the human internal anal sphincter: the role of nitric oxide by T. O'Kelly and others>[abstract, organ-bath tension measurements and field stimulation]{ref}
Several interventions converged on the same explanation. A compound releasing <nitric oxide> relaxed the strips; inhibitors of <nitric oxide synthase> suppressed electrically evoked relaxation; adding the appropriate form of <arginine> reversed that inhibition. The opposite <enantiomer> did not have the same effect. A substance that scavenges <nitric oxide> also abolished the response. This combination of mimicry, inhibition, rescue and specificity controls supported a role for <nitric oxide> in neural relaxation of <smooth muscle>. It provided stronger causal evidence than observing a correlation between chemical abundance and relaxation alone.<Nerve mediated relaxation of the human internal anal sphincter: the role of nitric oxide by T. O'Kelly and others>[abstract, donor, inhibitor, enantiomer and scavenger controls]{ref}
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