Résumé
OBJECTIVE:To study the vasodilatation effects of the alcohol extract from Uighur medicine Ziziphora clinopodioi-des(EEZ)on isolated rat thoracic aorta vessel rings. METHODS:Isolated rat thoracic aorta vessel rings were prepared. There was a group with intact vessel ring endothelium and a group with vessel ring endothelium removed in the test. After preshrinking the ves-sel rings with phenylephrine(PE),EEZ of 100,300,500,700,900 and 1 100 mg/L was added gradually,concentration-vasodila-tation curve was drawn and maximal vasodilatation rate (Emax) and median effective concentration (EC50) were calculated. For the group with vessel ring endothelium removed,after the vessel ring was pretreated with EEZ at EC50 in calcium-free solution or calci-um-free high-potassium solution,CaCl2 of 0.4,0.8,1.2,1.6,2.0 and 2.4 mmol/L was added gradually,and calcium concentra-tion-tension curve was drawn;following the pretreatment of the vessel ring with EEZ at EC50,1 μmol/L PE was added and shrink tension was recorded and vasoconstriction percentages was calculated. RESULTS:EEZ had vasodilatation effect on the vessel ring preshrunk with PE in a concentration and smooth muscle-dependent manner. The group with intact vessel ring endothelium and the group with vessel ring endothelium removed respectively had Emax of (58.18 ± 16.23)% and (73.54 ± 17.21)%,and EEZ EC50 of 773.27 mg/L. For calcium-free high-potassium solution,EEZ could cause the calcium ion-vasoconstriction curve to move to the right obviously;for calcium-free solution,EEZ could inhibit the vasoconstriction caused by PE. CONCLUSIONS:EEZ has vasodi-latation effects by a mechanism which may be related to inhibiting calcium influx and intracytoplasmic calcium release through the inhibition of voltage-dependent calcium channels(VDCCs),and thus interfering intracytoplasmic calcium ion balance.
Résumé
AIM: To observe the hypotensive effect of melatonin (MT) on two-kidney one-clip renal hypertensive (2K1C) rats and to explore its aortic mechanism. METHODS: 2K1C rats were obtained by narrowing the left kidney artery; systolic blood pressure was measured by use of tail-cuff method; vascular actions of MT were measured using isolated blood vessel method. RESULTS: MT reduced blood pressure of 2K1C rat significantly [(C23.45 ± 2.40) kPa versus (19.81 ± 2.78) kPa, P < 0.05]; MT (10-4 mol • L-1), restored vasodilation to acetyl-choline partially (P < 0.01) and attenuated vasoconstriction to norepinephrine (P < 0.05) in isolated aortic rings from 2K1C rats. MT(10-5 ∼ 10-3 mol • L-1) also inhibited vasoconstriction of aortic rings to KCl (70 mmol · L-1) and this action had no significant difference in sham and 2K1C rats. CONCLUSION: Vascular activities of MT is one of the factors involved in its hypotensive effect. MT restores the endothelial dysfunction and the balance of oxidative condition in smooth muscle cell by its free radical scavenging and antioxidant properties.
Résumé
0.05). Conclusions HF could not only relax cerebral vessels, reduce the CVR and enhance the CBF, but also dilate the femoral vessels of CVS dogs. Nevertheless, the latter action was much weaker. Furthermore, there was no relationship between effects of HF on vascular relaxation and contraction activity and the blood vessel endothelium.
Résumé
AIM To observe the hypotensive effect of melatonin (MT) on two-kidney one-clip renal hypertensive (2K1C) rats and to explore its aortic mechanism. METHODS 2K1C rats were obtained by narrowing the left kidney artery; systolic blood pressure was measured by use of tail-cuff method; vascular actions of MT were measured using isolated blood vessel method. RESULTS MT reduced blood pressure of 2K1C rat significantly 〔(23.45?2.40) kPa versus (19.81?2.78) kPa, P