The Potential Involvement of an ATP-Dependent Potassium Channel-Opening Mechanism in the Smooth Muscle Relaxant Properties of Tamarix dioica Roxb.

Abstract

Background: Tamarix dioica is traditionally used to manage various disorders related to smooth muscle in the gastrointestinal, respiratory, and cardiovascular systems. This study was planned to establish a pharmacological basis for the uses of Tamarix dioica in certain medical conditions related to the digestive, respiratory, and cardiovascular systems, and to explore the underlying mechanisms. Methods: A phytochemical study was performed by preliminary methods, followed by HPLC-DAD and spectrometric methods. In vivo evaluation of a crude hydromethanolic extract of T. dioica (TdCr) was done with a castor-oil-provoked diarrheal model in rats to determine its antidiarrheal effect. Ex vivo experiments were done by using isolated tissues to determine the effects on smooth and cardiac muscles and explore the possible mechanisms. Results: TdCr tested positive for flavonoids, saponins, phenols, and tannins as methanolic solvable constituents in a preliminary study. The maximum quantity of gallic acid equivalent (GAE), phenolic, and quercetin equivalent (QE) flavonoid content found was 146 ± 0.001 μg GAE/mg extract and 36.17 ± 2.35 μg QE/mg extract. Quantification based on HPLC-DAD (reverse phase) exposed the presence of rutin at the highest concentration, followed by catechin, gallic acid, myricetin, kaempferol, and apigenin in TdCr. In vivo experiments showed the significant antidiarrheal effect of TdCr (100, 200, and 400 mg/kg) in the diarrheal (castor-oil-provoked) model. Ex vivo experiments revealed spasmolytic, bronchodilatory, and vasorelaxant activities as well as partial cardiac depressant activity, which may be potentiated by a potassium channel opener mechanism, similar to that of cromakalim. The potassium channel (KATP channel)-opening activity was further confirmed by repeating the experiments in glibenclamide-pretreated tissues. Conclusions: In vivo and ex vivo studies of T. dioica provided evidence of the antidiarrheal, spasmolytic, bronchodilator, vasorelaxant, and partial cardiodepressant properties facilitated through the opening of the KATP channel.

Genus Parkia: Phytochemical, Medicinal Uses, and Pharmacological Properties

“…These effects could be attributable to its inhibitory capacity on the propulsive movement of gastrointestinal tract smooth muscles [ 45 ]. Medicinal plants are believed to exert antidiarrheal activity by enhancing the opening of intestinal potassium channel and stimulating Na + /K + -ATPase activity, as well as decreasing intracellular calcium concentration, which then promotes gastrointestinal smooth muscle relaxation, leading to diminished diarrhea [ 194 , 195 , 196 ]. The potential of these plants as agents to reduce diarrhea can be explored further in irritable bowel syndrome or chemotherapy-induced diarrhea.…”

The Spasmolytic Effect of Astragalus Sarcocolla on the Intestinal Smooth Muscles of Rabbit In Vitro: Potassium Channel Opening

“…When tested in the presence of glibenclamide, which is a specific blocker of the ATP-dependent K + channels [23], the inhibitory effect of the ASE extract was found to be decreased (Figure 4). These results clearly and strongly indicate that the spasmolytic effect of the plant extract is mediated possibly through ATP-dependent K + channel activation [19]. However, because of the non-availability of a standard potassium channel opener, ASE was not compared with it.…”

“…The spontaneous contractions were then recorded and the spasmolytic effect of drugs was analyzed without directly applying any agonist or antagonist drug. ASE was then added in a cumulative manner with the final concentration of 0.04-8 mg/ml into the tissue bath containing Tyrode's solution to record its relaxant effect on the ileum [19].…”

Studies to Elucidate the Mechanism of Cardio Protective and Hypotensive Activities of Anogeissus acuminata (Roxb. ex DC.) in Rodents

“…During in vitro studies, Anogeissus acuminata crude extract's (Aa.Cr) potential effect was evaluated in rabbit paired atrial preparations, and it demonstrated increased negative ionotropic and chronotropic effects, with a gradual increase in tissue bath concentration comparable with the standard calcium antagonist Verapamil being used. Cytosolic calcium ions' reduced availability is likely to be responsible for the demonstrated effect of plant extract and Aa.Cr increased cardio depressant effect with the increasing dose, supposedly due to the presence of calcium channel blocking effects [31].…”

“…Power Lab bonded with computer exhibit recording of spontaneous atrial beating carried out with force displacement transducer. Displaying of spontaneous tissue beating at 1 g resting tension is due to occurrence of pacemaker cells [31].…”