[Vascular effect of extract from mulberry leaves and underlying mechanism].
To investigate the vascular activity of extract from mulberry leaves (EML) on rat thoracic aorta and the underlying mechanism.



Isolated thoracic rings of Sprague-Dawley rats were mounted on the organ bath and the tension of the vessel was recorded.



(1) EML produced a concentration-dependent vasorelaxation of aorta preconstricted by high K(+) (60 mmol/L) or 10(-6) mol/L phenylephrine (PE) in endothelium-intact and endothelium-denuded arteries. (2) EML at EC(50) concentration reduced the calcium dose-response curve. (3) After incubation of aorta with verapamil, EML induced vasocontraction of aorta preconstricted by PE, which was abolished by ruthenium red.



The vascular effect of EML is biphasic, the vasorelaxation is greater than the vasocontraction. The vasorelaxation induced by EML may be mediated by inhibition of voltage-and receptor-dependent calcium channels in vascular smooth muscle cells, while the vasocontraction is via activation of ryanodine receptor in endoplasmic reticulum.
Xia
Man-Li
ML
Department of Physiology, Medical School, Jiaxing College, Jiaxing 314001, China.
Gao
Qin
Q
Zhou
Xin-Mei
XM
Qian
Ling-Bo
LB
Shen
Zhong-Hua
ZH
Jiang
Hui-di
HD
Xia
Qiang
Q
D000085:Acetates / Q000302:isolation & purification / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D031625:Morus / Q000737:chemistry*; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*
D000085:Acetates; D010936:Plant Extracts; D019837:Ryanodine Receptor Calcium Release Channel; D011188:Potassium