Abstract
ABSTRACT
An in vitro dose-response study was performed to determine the effects of aerosolized amiloride on transepithelial potential difference and mucociliary velocity. A preparation of isolated frog palate (Rana sculenta) was used for two groups: one submitted to amiloride nebulization (n = 7) and a control group submitted to vehicle (NaCl 0.45%) nebulization (n = 7). Transepithelial potential difference was measured by means of agar-filled microelectrodes connected to the high input of a grounded electrometer. Mucociliary velocity was determined by monitoring the movement of aluminum disks as tracer particles. Amiloride nebulization caused a significant dose-dependent increase in mucociliary velocity when compared to the control group (p < 0.05). The amiloride also turned the luminal surface more positive, promoting a decrease (in absolute value) in transepithelial potential difference when compared to the control group (p < 0.05). A positive and continuous (quadratic) association between mucociliary velocity and transepithelial potential difference was verified in the group treated with amiloride (p = 0.019). The results presented are in agreement with a decrease in mucus rigidity due to increased hydration of the mucous gel, induced by the blockade of sodium channels by the drug. In the range of concentrations used in this study (10−7 to 10−3 M amiloride in NaCl 0.45% solution) there was no evidence of uncoupling between the mucous gel and the tips of the cilia. The model should prove to be valuable for studying agents which can act as modulators of transepithelial ionic conductance.
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