[The effect of 18beta-glycyrrhetinic acid on gap junction among cerebral arteriolar smooth muscle cells in Wistar rat and spontaneously hypertensive rat].
OBJECTIVE
This study compared Wistar rat with spontaneously hypertensive rat (SHR) on the electrophysiology and coupling force of the smooth muscle cells in the cerebral arteriolar segments and observe the influence of 18beta-glycyrrhetinic acid(18beta-GA) on the gap junctions between the arterial smooth muscle cells.


METHODS
The outer layer's connective tissue of the cerebral arteriolar segments was removed. Whole-cell patch clamp recordings were used to observe the 18beta-GA's impaction on the arteriolar segment membrane's input capacitance (C(input)), input conductance (G(input)) and input resistance (R(input)) of the smooth muscle cells.


RESULTS
(1) The C(input) and G(input) of the SHR arteriolar segment smooth muscle cells was much higher than the Wistar rats, there was significant difference (P < 0.05). (2) 18beta-GA concentration-dependently reduced C(input) and G(input) (or increase R(input)) on smooth muscle cells in arteriolar segment. IC50 of 18beta-GA suppression's G(input) of the Wistar rat and SHR were 1.7 and 2.0 micromol/L respectively, there was not significant difference (P > 0.05). After application of 18beta-GA concentration > or = 100 micrmol/L, the C(input), G(input) and R(input) of the single smooth muscle cells was very close.


CONCLUSIONS
Gap junctional coupling is enhanced in the SHR cerebral arterial smooth muscle cells. 18beta-GA concentration-dependent inhibits Wistar rat's and SHR cerebral arteriolar gap junctions between arterial smooth muscle cells. The inhibitory potency is similar between the two different rats. When 18beta-GA concentration is > or = 100 micromol/L, it can completely block gap junctions between arteriolar smooth muscle cells.
The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Department of Physiology, School of Medicine, Shihezi University, Shihezi 832002, China.
Xin-Yan
XY
Chen
Jun-Qiang
JQ
Si
Li
L
Li
Lei
L
Zhao
Li-Li
LL
Wei
Xue-Wei
XW
Jiang
Ke-Tao
KT
Ma
D000818:Animals; D002536:Cerebral Arteries / Q000166:cytology; D017629:Gap Junctions / Q000187:drug effects*; D006034:Glycyrrhetinic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar
C119129:18alpha-glycyrrhetinic acid; D006034:Glycyrrhetinic Acid