Effect of mefloquine on the mechanical activity of the mouse isolated rectal smooth muscle

Abstract

Summary:The effects of mefloquine on the mechanical activity of the mouse isolated rectal smooth muscle was studied. Mefloquine (4.1x10-5 -5.2x10 -3 M) when applied alone and separately exerted variable effects on the rectum. In some preparations, it caused slight phasic contractions while in others no response was elicited. When the external (Ca 2+ ) was increased from 1.8mM to 300mM mefloquine produced phasic contractile activity which was abolished on return to normal 1.8mM suggesting that the contractile activity was due to extracellular Ca 2+ influx. Meflaquine (4.1x10-6M -4.1x10 -4 M) caused contraction -dependent inhibition of KCL, Carbachol and CaCl 2 (in depolarizing Tyrode Solution). Mefloquine (2.1x10 -4 M) blocked KCL, but not carbachol contractions which were largely reversed by increasing (Ca 2+ ). The results show that mefloquine possesses anticholinergic and appreciable calcium channel blocking activity.

Effect of Dihydroartemisinin on contractility to Drugs in isolated smooth muscle Preparations in guinea pig in vitro models

“…In some preparations it showed no response, while in others it produced slight phasic contraction when external calcium (Ca 2+ ) ion was introduced. The slight phasic contractile activity was abolished when verapamil(5x10 -3 mg/ml) was added to the organ bath fluid.This observed results of no contractile responses when dihydroartemisin was applied alone, was similar with report on chloroquine which producedno contractile responses when applied on the rat urinary bladder strip underbaseline conditions [10]. The antagonism by dihydroartemisininin each instance, for example ( Ach.…”

“…>Histamine )was non-competitive ,this is basically proven by the agonist -concentration response curves which were clearly displaced to the right in asymmetric non -parallel fashion , withdepressed maxima (Figure 1and 2). It had been an establishedprinciple that, contractile responses induced by acetylcholine is influenced mainly by the stimulation of\muscarinic receptors [11]; On the other hand, theobserved slight contractile responses, were reversibly abolished due to the introduction of zero Ca 2 + in physiological solution. KCl-induced contractions are largely reported to be due to a depolarizing action on the plasma membrane of the rat urinary bladder, as a result of which extracellular Ca 2 + influx occurs via voltage -dependent Ca 2 + channels (VOCs); [18, 19, 20; 21].…”

“…Research work on the mechanical activity of muscles on ancient antimalarials such as chloroquine, mefloquine ,quinine in animal models had been carried out extensively 8,9,10, 11 .studied the effects of chloroquine on the rat urinary bladder strip . On the contrary, few studies so far have been carried out on the effect of Artemisinin derivatives on muscle contractility ;,Ejiofor et al, studied the effects of artemether on uterine muscle 12 ,The effect of artesunate on guinea pig ileum wasinvestigated 13 .…”

Effect of artemether on the mechanical activities of isolated smooth muscles of non-pregnant uterus and ileum in mice and wistar rats

“…The methods as described by Unekwe, [11] were adopted. A vertical strand of isolated ileal smooth muscle tissue of about 2 cm was gently picked using forceps; needle and white thread was passed through the tissue and tied through the arm of the frontal lever to the tissue holder.…”

“…Research work on the mechanical activity of muscles on ancient antimalarials such as chloroquine, mefloquine, quinine in animal models had been carried out extensively [7][8] [9][10] [11]. On the contrary, few studies so far have been carried out on the effect of Artemisinin derivatives on muscle contractility [12].…”