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J Sex Med. 2013 Jul;10(7):1720-9. doi: 10.1111/jsm.12183. Epub 2013 May 13.

Endothelium-independent relaxant effect of Rubus coreanus extracts in corpus cavernosum smooth muscle.

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  • 1Department of Urology, National Police Hospital, Seoul, Korea.

Abstract

INTRODUCTION:

Rubus coreanus is a perennial shrub native to the southern part of the Korean peninsula. Although it is known that R. coreanus has a dose-dependent relaxation effect on rabbit corpus cavernosum (CC), the exact mechanism of action by which R. coreanus work is not fully known.

AIMS:

To elucidate the direct effects of unripe R.‚ÄČcoreanus extract (RCE) on CC smooth muscle cells.

METHODS:

Dried unripe R. coreanus fruits were pulverized and extracted with 95% ethanol. Isolated rabbit CC strips were mounted in an organ-bath system, and the effects of RCE were evaluated. To estimate [Ca(2+)]i , we used a Fura-2 fluorescent technique.

MAIN OUTCOME MEASURES:

The effects of unripe RCE on ion channels and the intracellular Ca(2+) concentration ([Ca(2+)]i ) of CC.

RESULTS:

RCE effectively relaxed phenylephrine (PE)-induced tone in rabbit CC, and removal of the endothelium did not completely abolish the relaxation effect of RCE. Tetraethylammonium (1 mM) did not inhibit RCE-induced relaxation in strips precontracted by PE in the organ bath. However, CaCl2 -induced constriction of CC strips, bathed in Ca(2+)-free buffer and primed with PE, was abolished by RCE. In addition, RCE decreased basal [Ca(2+)]i in corporal smooth muscle cells. The increases of [Ca(2+)]i evoked by 60 mM K(+)-containing solution in A7r5 cells were suppressed by RCE, and RCE relaxed KCl-induced tone in endothelium-free CC, which indicated that RCE blocked the voltage-dependent Ca(2+) channels (VDCCs). RCE decreased basal [Ca(2+)]i and the [Arg8]-vasopressin-induced [Ca(2+)]i increases in A7r5 cells, and RCE inhibited the contraction of endothelium-free CC induced by PE in Ca(2+)-free solution, which suggested that RCE might act as a modulator of corporal smooth muscle cell tone by inhibiting Ca(2+) release from sarcoplasmic reticulum.

CONCLUSION:

RCE acts through endothelium-independent and endothelium-dependent pathways to relax CC. RCE may inhibit VDCCs and Ca(2+) release from sarcoplasmic reticulum.

© 2013 International Society for Sexual Medicine.

KEYWORDS:

Calcium Channels; Corpus Cavernosum Smooth Muscle; Erectile Dysfunction; Rubus Coreanus

[PubMed - indexed for MEDLINE]
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