A modified single sucrose gap. Junction potentials and electrotonic potentials in gastrointestinal smooth muscles.

Modifications were made to a rubber membrane type of single sucrose gap apparatus, which facilitated recording of isometric tension in smooth muscle preparations and which allowed electrotonic potentials and junction potentials to be evoked simultaneously. Nonadrenergic, noncholinergic inhibitory junction potentials were recorded from the circular muscle of the rat cecum. The amplitude of the inhibitory junction potential was linearly dependent on membrane potential, and inhibitory junction potential reversal potential was consonant with the expected potassium equilibrium potential. Cholinergic excitatory junction potentials were recorded in a preparation of the guinea pig cecum. It has been discussed as to how this type of modified single sucrose gap will be useful for pharmacological investigations into neuromuscular transmission, in addition to being a useful technique for examining actions of drugs and chemicals on smooth muscles.