Antitussive activity of Althaea officinalis L. polysaccharide rhamnogalacturonan and its changes in guinea pigs with ovalbumine-induced airways inflammation.

AIM: The presented studies were aimed on experimental confirmation of Althaea officinalis polysaccharide rhamnogalacturonan antitussive effect and its changes in conditions of allergic inflammation. METHODS: We have tested whether rhamnogalacturonan inhibits cough reflex and modulates airways reactivity of guinea pigs in vivo. The cough in guinea pigs was induced by 0.3 M citric acid (CA) aerosol for 3 min interval, in which total number of cough efforts (sudden enhancement of expiratory flow accompanied by cough movement and sound) was counted. Specific airway resistance and its changes induced by citric acid aerosol were considered as an indicator of the in vivo reactivity changes. RESULTS: 1) Althaea officinalis polysaccharide rhamnogalacturonan dose- dependently inhibits cough reflex in unsensitized guinea pigs. Simultaneously, plant polysaccharide shortened the duration of antitussive effect when it was been tested in inflammatory conditions. 2) Rhamnogalacturonan did not influence airways reactivity in vivo conditions expressed as specific resistance values neither sensitized nor unsensitized groups of animals. 3) The antitussive activity of codeine (dose 10 mg.kg(-1) b.w. orally) tested under the same condition was comparable to higher dose of rhamnogalacturonan in unsensitized animals. 4) The characteristic cellular pattern of allergic airways inflammation was confirmed by histopathological investigations. CONCLUSION: Rhamnogalacturonan isolated from Althaea officinalis mucilage possesses very high cough suppressive effect in guinea pigs test system, which is shortened in conditions of experimentally induced airways allergic inflammation (Tab. 1, Fig. 4, Ref. 25). Full Text in free PDF www.bmj.sk.

The influence of animal species on the relationship between ATP-sensitive potassium ion channels and defense reflexes of the airways.

BACKGROUND: The ATP-sensitive potassium ion channels (K+ATP) are widely expressed on airway sensory nerves that mediate cough and other protective reflexes; dependent on airways smooth muscles (ASM) reactivity. OBJECTIVE: The study was conducted to determine the involvement of K+ATP in airway sensory nerves activity of different animal species. METHODS: In this study we have evaluated the cough reflex inhibiting potential and modulation of ASM reactivity in vitro, by K+ATP opener-pinacidil in guinea pig and cats. The cough in guinea pig was induced by administration, in cats by mechanical stimulation of the airways. ASM reactivity was tested by organ tissue both method of 0.3 M citric acid aerosol at 3 min interval. RESULTS: 1) Pinacidil inhibits cough reflex in guinea pigs which was antagonized when pre-treated with K+ATP blocker glibenclamide. 2) Pinacidil exhibited antitussive activity in cats comparable to codeine and was noticeably higher than dropropizine effects. 3) ASM reactivity was significantly abolished by pinacidil and almost completely antagonized by glibenclamide in guinea pigs. 4) Pinacidil significantly attenuated ASM contraction in cats only in highest concentrations of contractile mediators. CONCLUSION: K+ATP may be involved in mechanisms of cough reflex, likewise in antitussive activity of several more agents and also on defence reflexes dependent on ASM reactivity in different animal species such as guinea pigs and cats (Fig. 8, Ref. 20). Full Text (Free, PDF) www.bmj.sk.

Possible mechanisms of dose-dependent cough suppressive effect of Althaea officinalis rhamnogalacturonan in guinea pigs test system.

The rhamnogalacturonan, isolated from the roots of medicinal plant Althaea officinalis L., showed various biological effects on the citric acid-induced cough reflex and reactivity of airways smooth muscle in vitro and in vivo conditions. It possessed dose-dependent cough suppression effect comparable with opioid agonist codeine. However, reactivity of the airways smooth muscle, measured in vitro as well as in vivo conditions was not significantly affected by rhamnogalacturonan and thus bronchodilatory activity did not participate in the cough suppression effect of polysaccharide tested. Moreover, the cough suppression effect of the polymer was not significantly modified by pretreatment of K(+)(ATP) ion channels with selective antagonist and therefore activation of this type of ion channels is not involved in the mechanism of rhamnogalacturonan cough suppressive ability. On the contrary, pretreatment of animals with selective 5-HT(2) receptors antagonist significantly decreased rhamnogalacturonan antitussive efficacy. From this point of view it seems that the cough suppression effect of the polymer is associated with the serotonergic 5-HT(2) receptor's function.

Age-dependent changes of airway obstruction parameters.

The study was aimed at the assessment of the physiological range of phi and Tme/Te indices in children of up to 24 months of age, as based on noncalibrated respiratory inductive plethysmography performed in the supine position. We also examined the dependence of these indices on children's age and sex. The study was carried out in 127 healthy children. The results of the study indicate a significant decrease of phi in children aged 7-24 months in comparison with children of up to 6 months of age (P<0.001). Similarly, values of Tme/Te were found significantly higher in the group of older children (P<0.05). We did not find any appreciable sex differences in both measured parameters. The results of this study suggest that the Tme/Te index might be more stable, less age-dependent parameter of the Respitrace measurement than the phase angle j, but further research and analysis to achieve a correct verdict are warranted.