Mediators and intracellular mechanisms of NANC relaxation of smooth muscle in the gastrointestinal tract

Abstract

Tension of the skeletal muscle is solely controlled by excitatory cholinergic motor neurons. By contrast, the peripheral smooth muscle tissues are dual-controlled by nonadrenergic noncholinergic (NANC) inhibitory neurons as well as excitatory neurons. In the gastrointestinal tract, many possible candidates, including peptides, amino acids, nucleotides and gaseous compounds, for the inhibitory mediator and mechanisms of their inhibitory control have been extensively studied. This article introduces the diversity of inhibitory mediators and their probable intracellular mechanisms on the basis of recent findings on this theme, many of which are unexpected interesting findings.