Short communication - URINARY BLADDER RELAXANT EFFECT OF ARTEMISIA VULGARIS AND ASPALATHUS LINEARIS.
In isolated rabbit urinary bladder preparations, Artemisia vulgaris (Av.Cr) crude extract inhibited the contractions produced by carbachol (CCh, 1 M) and high K+ (80 mM) in a concentration-dependent (0.03-10 mg/mL) manners. The crude extract of Aspalathus linaeris (Al. Cr) relaxed the contractions produced by low K+ (25 mM) at concentration range of 0.3-1.0 mg/mL, having moderate inhibitory effect on contractions produced by K+ (80 mM). Contractions induced by low K+ were partially antagonized by glibenclamide (3 M). These results indicate that urinary bladder relaxation produced by Artemisia vulgaris extract is mediated via dual, anticholinergic and Ca++ antagonist mechanisms, while that of Aspalathus linaris via dominant KATP channel opening and weak Ca++ channel blockade pathways. Thus the present study reveals the Artemisia vulgaris and Aspslathus linaeris medicinal usefulness in hyperactive bladder disorders
Key words: Artemisia vulgaris, Aspalathus linaris, urinary bladder relaxation.
Hyperactivity of urinary bladder is mostly associated with urinary frequency and nocturia, resulting due to their involuntary contraction which leads to incontinence with and without urge. All of these symptoms are usually experienced by patients during filling phase of micturition cycle due to involuntary contractions of the bladder. Symptoms associated with dysfunction of the bladder are highly prevalent which deeply impair the quality of life of peoples, resulting in socio-economic burden on society. Urinary bladder contractility is predominantly controlled by muscurinic acetylcholine receptor system (Borchert et al., 2004). We previously observed that Artemisia vulgaris Linn. commonly known as Mugwort (Compositae) exhibits antispasmodic, bronchodilatory and antidiarrheal properties , which is mediated through dual pathways i.e. Ca++ antagonist and anticholinergic (Khan and Gilani, 2009).
Similarly, Aspalathus linaeris Burm. (Rooibos tea, Fabaceae) is reported to possess spasmolytic, airways relaxation, hypotensive and vasodilatory effects, occurred via predominant K+ channel activation and weak Ca++ channel blockade mechanisms (Gilani et al., 2006; Khan and Gilani, 2006, 2010). In present research, Artemisia vulgaris and Aspalathus linearis were investigated for the possible urinary bladder-relaxant action.
MATERIALS AND METHODS
Extraction of plant material: Artemisia vulgaris aerial parts were collected and shade dried followed by crushing. Then the crushed plant material was soaked in hydro-methanol (70%), filtered through filter paper and evaporated to obtain crude extract of Artemisia vulgaris (Av.Cr). Aspalathus linearis aqueous concentrate was evaporated at 450C in rotary evaporator to obtain brown colored crude extract of Aspalathus linaris (Al. Cr).
Rabbit urinary bladder tissues: From rabbit whose neck was cervically dislocated, urinary bladder was isolated and sectioned into four vertical strips (Gilani et al., 2008). Each tissue was hanged in tissue bath filled with 20 mL of Kreb's-Henseleit solution (pH 7.4), supplied continuously with carbogen gas. The inhibitory effects of the test material against CCh and/or K+ induced contractions were evaluated by adding test stock solution in cumulative fashion. The results observed after applying test materials were evidenced through Grass Model 7 Polygraph (Grass instrument company, USA).
When tested in urinary bladder strips, Av.Cr relaxed the contractions produced by K+ (80 mM) and CCh (1 M) (Figure 1), resulting with EC50 values of 0.26 (0.14-0.5, 95% CI, n=4) and 3.4 mg/mL (2.5-4.9, n=4) respectively. On the other hand Al. Cr weakly effected (40%, n=3) the contractions produced by K+ (80 mM), while full relaxation was observed when applied on contractions produced by K+ (25 mM). The EC50 value of 0.34 mg/mL (0.13-0.44, n=4) was calculated. In the presence of glibenclamide (3 M), the inhibitory effect of Al.Cr was partially blocked against K+ (25 mM)-induced contraction and right shift in the curve was observed with an EC50 value of 2.4 mg/ml (1.6-3.7, n=4) as shown in Figure 2.
In traditional system of medicine, Artemisia vulagaris and Aspalathus linearis are considered useful therapeutic agents in relieving smooth muscle spasms (Duke et al., 2002). We therefore examined their effects on urinary bladder contractility. As expected, Artemisia vulagaris and Aspalathus linearis caused relaxation of urinary bladders tissues via various pharmacological mechanisms. The Artemisia vulagaris extract inhibited contractions induced by CCh more effectively than contractions induced by high K+, indicating that it mediate urinary bladder relaxation through dual muscarinic receptors and Ca++ entry blockade. Aspalathus linearis produced glibenclamide, a KATP channel blocker (Gopalakrishnan et al., 2004) resistant inhibition of contractions produced by low K+, and with moderate effect against high K+. All of this reveals that a dual pathway of dominant ATP-dependent K+ channel opening and weak Ca++ antagonism account for its urinary bladder relaxant effect.
It is known that anticholinergics, Ca++ channel blockers and K+ channel activating agents are the potential drugs for treatment of bladder hyperactivity (Empfield et al., 1995; Andersson et al., 2001). In conclusion, Artemisia vulagaris and Aspalathus linearis showed urinary bladder relaxant activity. Further detail clinical studies are warranted to confirm their pharmaceutical efficacy in remedy of overactive status of the urinary bladder.
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Khan, A. U., and A. H. Gilani (2010). In vivo studies on bronchodilatory and analgesic activities of Hysocyamus niger and Aspalathus linearis. Lat. Am. J. Pharm. 29:777-782.
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|Publication:||Journal of Animal and Plant Sciences|
|Date:||Dec 31, 2015|
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