Effects of Paeoniflorin on the activity of muscle strips, intracellular calcium ion concentration and L‑type voltage‑sensitive calcium ion channels in the sphincter of Oddi of hypercholesterolemic rabbits.

Sphincter of Oddi dysfunction (SOD) is a benign obstructive disorder predominantly resulting from spasms of the SO. Pharmacological therapies aim to induce SO relaxation; the hypercholesterolemic (HC) rabbit is the only SOD model available for study. In the present study, SO muscle strips, intracellular calcium ion concentrations and the mRNA expression levels of the alpha 1C subunit of the L-type calcium channel in the SO muscle cells of HC rabbits were employed to investigate the effects of paeoniflorin (PF). Alterations in L-type calcium channel alpha subunit 1C mRNA and protein expression in SO cells with HC following the application of different concentrations of PF were determined by reverse transcription-quantitative polymerase chain reaction and western blotting. The whole cell patch clamp technique was used to observe the effects of different concentrations of paeoniflorin on L-type calcium channel current. The results of the present study demonstrated that PF induced the relaxation of SO muscle strips and reduced the intracellular calcium concentration in the SO muscle cells of HC rabbits. In addition, PF decreased the mRNA expression levels of the alpha 1C subunit of the L-type calcium channel and reduced the L-type calcium channel current in SO cells. These results suggested that the mechanism underlying the relaxation of the SO muscle by PF may be associated with the reduction of calcium ion influx via L-type calcium channels.