[Vasorelaxational effects of procyanidins on rabbit aorta in vitro and decreasing arterial blood pressure in vivo].
OBJECTIVE
To study the vasodilation effect of the procyanidin (PC) extracted from grape seeds on rabbit thoracic aortic rings in vitro, decreasing blood pressure in vivo and the possible mechanism.


METHODS
Rabbits aortic rings were isolated and were divided into six groups including removal of endothelium, integrity of endothelium, 1 x 10(-5) mol X L(-1) indomethacin (Indo), 1 x 10(-5) mol x L(-1) propranolol (Prop), 1 x 10(-4) mol x L(-1) N(omega)-nitro-L-arginine (L-NNA) and 1 x 10(-5) mol x L(-1) methylene blue (MB). Then the thoracic aortic rings were treated with PC with cumulative concentrations of 1.25, 2.5, 5.0 mg x L(-1) respectively and the changes of tension were recorded, and investigate the effect of 40 mg x L(-1) PC on the contraction of aortic smooth muscles, thoracic aortic rings were pre-treated with NA (1 x 10(-8) to approximately 1 x 10(-5) mol x L(-1)), KCl (6.3 to approximately 100 mmol x L(-1)) and CaCl2 (1 x 10(-5) to approximately 1 x 10(-5) mol x L(-1)) followed by treatment with PC. Then, rabbits common carotid artery was intubated and arterial blood pressure in vivo was recorded. PC with cumulative concentrations of 4.0, 8.0, 16, 32, 64, 84 mg x kg(-1) was injected into vein and the changes of arterial blood pressure were observed.


RESULTS
PC could relax isolated rabbit aorta and showedan obvious concentration-dependent relaxation (r = 0. 63, P < 0.001). The relaxant effect of PC was significantly reduced by removal of endothelium and by treatment with nitric oxide synthase inhibitor L-NNA, or guanylyl cyclase inhibitor MB. In addition PC could decrease the dose response curves of aortic rings to NA, KCl and CaCl2. PC has a significant concentration-dependent negative effect on arterial blood pressure in vivo (r = 0.92, P < 0.001).


CONCLUSIONS
PC has a vasodilation effect not only in an endothelium-dependent, nitric oxide involved manner, but in inhibition of calcium release and blockage of potential-dependent calcium channels. PC could decrease the rabbit's arterial blood pressure significantly in vivo.
Department of Physiology, North sichuan Medical College, Nanchong 637007, China.
Tuan-xiao
TX
Zhang
Cai-qin
CQ
Niu
Jian-min
JM
Hu
Hong
H
Liu
Hua-e
HE
Jing
D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology*; D002122:Calcium Chloride / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D044945:Proanthocyanidins / Q000494:pharmacology*; D011817:Rabbits; D014665:Vasodilator Agents / Q000494:pharmacology*
D044945:Proanthocyanidins; D014665:Vasodilator Agents; D011189:Potassium Chloride; D002122:Calcium Chloride; D009638:Norepinephrine