[Preliminary study on the mechanism of spontaneous rhythmic contraction in rabbit portal vein]

This study sought to probe into the mechanism of spontaneous contraction of portal vein. The morphological and electrophysiological characteristics of the freshly isolated interstitial cells (ICs) of rabbit portal vein were investigated by using immunohistochemical and conventional whole-cell patch clamp techniques. The isolated interstitial cells exhibited stellate-shaped or spindle-shaped bodies with a variable number of thin processes projecting from cell bodies, and these cells were noted to be c-Kit immunopositive. Under conventional whole-cell patch clamp configuration, the membrane potential was held at -60 mV, the spontaneous rhythmic inward currents were recorded in ICs, and the frequencies of which were similar to those of spontaneous contraction of portal vein. The inward currents were insensitive to nicardipine (an L-type calcium channel blocker) but could be abolished by gadolinium (a non-selective cation channel blocker). The results suggested that the spontaneous rhythmic inward currents recorded in freshly isolated ICs may be pacemaker currents which elicit the spontaneous contraction of portal vein.