Effects of selective K(+)-channel agonists and antagonists on myoelectrical activity of a locus of the small bowel.

Effects of Ca(2+)-activated K+ and voltage-activated K(+)-channel agonists and antagonists on the myoelectrical and contractile activity of a locus of the small bowel are simulated numerically. The model assumes that the electrical activity of smooth muscle syncytium is defined by kinetics of a mixture of L- and T-type Ca(2+)-channels, Ca(2+)-activated K+ and voltage-activated K(+)-channels, and leak Cl(-)-channels, and that the smooth muscle syncytium of the locus is a null-dimensional contractile system. The results of modelling, both qualitatively and quantitatively, reproduce the effects of forskolin, lemakalim, phencyclidine, charybdotoxin and high concentration of external K+ ions, on gastrointestinal motility. This is confirmed by comparison with experimental observations conducted on the smooth muscle preparations of different species.