Abstract:

Abstract:Objective
To discuss the influence of 18β-glycyrrhetinic acid (18βGA) on gap junction of vascular smooth muscle cells (VSMC)  and provide experimental basis for powerful and reversible gap junction inhibitors. Methods The preparations of mesenteric artery (MA) and anterior inferior cerebellar artery (AICA) (OD<100  μm) in guinea pig were digested with collagenase A and   its adventitial tissues were cleaned. Whole-cell patch clamp recordings were used to study the effect of 18βGA on membrane input capacitance (C_input),membrane input conductance (Ginput) or membrane input resistance (R_input) of VSMCs embedded in arteriole segments. Results The C_input and Ginput of the in situ cells were about 10-20 times that of the respective dispersed cell in MA and AICA. 18βGA concentration-dependently and reversibly suppressed Ginput or increased R_input,with  IC50 of 3.5 and 2.3  μmol·L^-1 in acutely isolated MA and AICA segments respectively. There was not significant difference between MA and AICA(P>0.05). After application of 18βGA (≥30  μmol·L^-1),the Cinput,G_input and Rinput of the in situ cells were very close to the respective dispersed cell in MA and AICA(P>0.05).
Conclusion 18βGA is a powerful and reversible gap junction blocker,achieving a maximal effect at ≥30  μmol^·L-1^. No significant difference is observed between MA and AICA for the gap junction blockade potency,suggesting a homogeneous property of the gap junctions between MA and AICA.

Key words: arteriole;18β-glycyrrhetinic acid;gap junction;patch clamp;smooth muscle cell