Antispasmodic Effects of Rooibos Tea (Aspalathus linearis) is Mediated Predominantly through K⁺‐Channel Activation

Abstract

Rooibos tea has been widely used for abdominal spasm and diarrhoea. The aim of the present study was to explore the possible mechanism for its use in such ailments. Its aqueous extract (RT) at 0.3-10 mg/ml produced relaxation of spontaneous and low K π (25 mM)-induced contractions of rabbit jejunum, with weak effect on high K π (80 mM)-induced contractions. In the presence of glibenclamide, relaxation of low K π -induced contractions was prevented. Cromakalim inhibited contractions induced by low K π , but not high K π , while verapamil did not differentiate in its inhibitory effect on contractions produced by the two concentrations of K π . RT also exhibited antidiarrhoeal and antisecretory activities in mice. The spasmolytic effect was concentrated in organic fractions. Its constituents, chrysoeriol, orientin and vitexin showed a similar pattern of spasmolytic effects to the extract, while rutin was more like verapamil. So Rooibos tea possesses a combination of dominant K ATP channel activation and weak Ca ππ antagonist mechanisms and hence justifies its use in hyperactive gastrointestinal disorders.

Antidiarrheal and antispasmodic activities of Salvia officinalis are mediated through activation of K+ channels

“…It showed a dose-dependent inhibitory effect on spontaneous contractions, thus showing that the observed antidiarrheal effect of the plant extract appears to be mediated through the presence of some gut relaxant component(s) in it. In our earlier studies, we observed that the spasmolytic effect of medicinal plants is usually mediated through K + channel opening (Gilani et al, 2005(Gilani et al, , 2006 or Ca ++ channel blockade (Bashir et al, 2011;Shah et al, 2011a). To assess, whether the spasmolytic effect of the crude extract of S. officinalis was also mediated via similar mechanism(s), it was tested on low K + (25 mM) and high K + (80 mM)-induced contractions.…”

“…To assess the involvement of K + channel opening (Gilani et al, 2006) and Ca ++ antagonist-like mechanisms (Bashir et al, 2011), the spasmolytic effect of the plant extract was tested on low K + (25 mM) and high K + (80 mM)-induced contractions in the isolated rabbit jejunum preparations. Following a sustained contraction in response to K + , the test material was added in a cumulative fashion to obtain the concentration-dependent inhibitory responses.…”

Vasodilator effect of 1-trifluoromethoxyphenyl-3-(1- propionylpiperidin-4-yl) urea is predominantly mediated through activation of voltage-dependent K+ channels

“…Previous studies have shown that vasodilator response of vessel is usually mediated through K + channel opening or Ca ++ channel blockade [15]. In order to characterize, whether the vasorelaxant effect of TPPU was mediated via similar pathways, its relaxant efficacy was tested against low K + (25 mM) and high K + (80 mM)-induced contractions [19].…”

“…To explore the participation of K + channel opening and/or Ca ++ channel antagonist properties [15], the vasorelexant effect of TPPU was further studied against low K + (25 mM) and high K + (80 mM)-induced contractions, respectively.…”

Antispasmodic Effect of Blackcurrant (<b><i>Ribes nigrum</i></b> L.) Juice and Its Potential Use as Functional Food in Gastrointestinal Disorders

“…In the digestive tract, Ach activates nicotinic receptors, which are present in vegetative ganglia, or muscarinic receptors found on smooth muscles and parasympathetic nerve fibers [25]. The stimulation of muscarinic receptors on the membrane of smooth muscles increases the intracellular calcium concentration [26][27][28]. Muscarinic receptors in the smooth muscles induce signal transduction mediated by G-protein and activate phospholipase-C, resulting in the production of inositol-triphosphate and diacylglycerol.…”