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Published on: October 11, 2014
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Quercetin relaxes guinea pig gallbladder strips.
Loren Kline1, Edward Karpinski2
1Department of Dentistry, 5-740 ECHA, University of Alberta, Edmonton, Alberta, Canada, T6G 1C9.
Nutrition Research (New York, N.Y.)
|November 21, 2016
Summary
Quercetin, a flavonoid, effectively relaxes gallbladder smooth muscle by inhibiting extracellular calcium entry. This relaxation is mediated through multiple signaling pathways, including protein kinase C, protein kinase A, and nitric oxide synthase.
Area of Science:
- Pharmacology
- Gastroenterology
- Smooth Muscle Physiology
Background:
- Quercetin, a well-known phytoestrogen and flavonoid, exhibits smooth muscle relaxant properties in vascular and intestinal tissues.
- The physiological effects of quercetin on gallbladder smooth muscle remain largely unexplored.
Purpose of the Study:
- To investigate the direct effects of quercetin on gallbladder smooth muscle.
- To elucidate the specific signaling pathways involved in quercetin-induced gallbladder smooth muscle relaxation.
Main Methods:
- An in vitro technique was employed to assess the relaxant effects of quercetin on isolated gallbladder smooth muscle strips.
- Concentration-dependent responses to quercetin were measured against cholecystokinin octapeptide (CCK-OP) and potassium chloride (KCl)-induced contractions.
- The involvement of protein kinase C (PKC), protein kinase A (PKA), intracellular calcium release, and nitric oxide synthase (NOS) pathways was examined using specific inhibitors.
Main Results:
- Quercetin significantly reduced both CCK-OP and KCl-induced tension in gallbladder smooth muscle in a concentration-dependent manner.
- Inhibition of PKC, PKA, and NOS significantly attenuated quercetin-induced relaxation, indicating their crucial roles.
- The use of 2-aminoethoxydiphenyl borate (2-APB), an inhibitor of intracellular calcium release, also significantly reduced quercetin-induced relaxation.
- Quercetin was found to block extracellular calcium entry, impacting downstream signaling events.
Conclusions:
- Quercetin demonstrates potent relaxant effects on gallbladder smooth muscle.
- The relaxation induced by quercetin is mediated through a complex interplay of multiple signaling pathways, including the inhibition of extracellular calcium influx and modulation of PKC, PKA, intracellular calcium release, and NOS activation.
