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Effects of total flavonoids of Hippophae rhamnoides on intracellular free calcium in vascular smooth
AIM: To explore effects of flavonoids of Hippophae rhamnoides ,quercetin and isorhamnetin on intracellular free calcium (
2+ >_i) in
vascular smooth muscle cells (VSMC) of spontaneously hypertensive rats (SHR) and wistar-kyoto rats(WKY) . METHODS: The effects of total flavonoid Hippopae rhamnoides (TFH) and its essential monomers,namely quercetin (Que) and isorhamnetin (Isor),on changes in
_i that occurred in cultured SHR and WKY vascular smooth muscle cells under initation of high K +,norepinephrine (NE) and angiotensin Ⅱ(AngⅡ) were detected with intracellular free Ca 2+ indicater fluo-3/AM. And compared with those of verapamil. RESULTS: (1)TFH 100mg·L -1 ,Que 0.1 mol·L -1 and Isor 0.1 mol·L -1 , on the resting VSMC _i,had no significant effect on WKY( P > 0.05 ),however,had some inhibitory effect on SHR( P <0.01). (2) High potassium increased VSMC _i more in SHR than in WKY( P <0.01),TFH 100 mg·L -1 ,Que 0.1 mol·L -1 and Isor 0.1 mol·L -1 inhibited the elevtaion of _i induced by high potassium-depolarization. These effects were similar to those of verapamil. The inhibitory effect on the _i elevation of SHR was more powerful than that on the _i elevation of WKY( P <0.01). (3) NE and AngII increased VSMC _i more in SHR than in WKY( P <0.01),TFH 100 mg·L -1 ,Que 0.1 mol·L -1 and Isor 0.1 mol·L -1 had markly inhibtory effect on the elevation of SHR and WKY _i induced by NE or Ang Ⅱ. (4) In the absence of extracellular Ca 2+ ,TFH, Que and Isor also had some blocking effects on the NE-induced SHR and WKY _i elevation,and inhibited the elevation of VSMC _i stronger in SHR than in WKY( P <0.01). CONCLUTION: TFH,Que and Isor may decrease the _i of VSMC by blocking both voltage-dependent calcium channels and receptor-operated calcium channels in physiological and pathological states,it is probable one of the impotant machnisms that TFH and its essential monomers have hypotensive effect and protective effect on target organs of patients.