Mucociliary wave pattern. A comparative analysis of extracellular and intracellular activities

Effects of neuropeptides on mucociliary activity

The effects of four neuropeptides, vasoactive intestinal polypeptide, enkephalin, bombesin, and substance P, on mucociliary activity in the rabbit maxillary sinus were investigated in vivo. The peptides were administered via the feeding artery (arteria maxillaris), and the resulting effects were registered with a noninvasive photoelectric technique. The peptides were tested in the dose range 0.0001 to 10 micrograms/kg body weight. The following results were observed: 1) vasoactive intestinal polypeptide and enkephalin did not influence mucociliary activity; 2) bombesin had only a slight accelerating effect on the mucociliary activity at doses of 0.1 to 10 micrograms/kg; and 3) substance P markedly accelerated the mucociliary activity in a dose-dependent manner in the dose range 0.01 to 10 micrograms/kg, the maximal increase being about 50%. The effect of substance P was atropine-resistant, and probably acted directly on the mucosa.

A versatile and quantitative computer-assisted photoelectronic technique used for the analysis of ciliary beat cycles

The beat cycles of rabbit tracheal cilia in culture and Mytilus laterofrontal cirri were recorded using a phototransistor, transillumination, video, and phase-contrast microscopy. The photoelectronic signal and video image of the ciliary activity were simultaneously recorded as a composite image. The photoelectronic signal was converted into a digital signal by a data acquisition system for further computer processing. By the selection of a small detector area and accurate detector alignment, a simple, repetitive photoelectronic signal representing ciliary activity was obtained. This signal records the ciliary beat frequency and demonstrates the triphasic nature of the beat cycle. The photoelectronic signal can be precisely correlated with the ciliary activity by analysis of the composite video recordings to provide the duration of the effective, recovery, and rest phases of the beat cycle. The video-photoelectronic signal correlations were verified by high-speed cinematography. High-speed films of ciliary activity were digitized, and the image density of selected pixels was analyzed by computer with respect to time and ciliary motion. These studies indicate that duration of the phases of the beat cycle are differentially reduced with increased beat frequency; the effective phase duration was quickly reduced to a minimum. This was followed by the reduction of the duration of the recovery phase to a minimum. The rest phase continues to be reduced without reaching a minimum, over the range of beat frequencies observed. These results suggest that ciliary beat frequency may be regulated either by modifying the rates of dynein-microtubule interactions or the rate of transition from one beat phase to the next.

Intracellular recording of potential oscillations in ciliated cells exposed to ionizing radiation

Intracellular potential oscillations of the ciliated cells of the rabbit's trachea have been measured by means of glass capillary microelectrodes during exposure of the cells to ionizing radiation. The electrophysiologic activity was fairly stable during the entire exposure at a total administered dose of 10.0 Gy. This finding is contradictory to the change in mucociliary activity obtained under the same conditions when measured with a light beam reflex method, but is in agreement with the findings regarding the influence of radiation on the membrane potentials as far as nerves and muscles are concerned.

A method for evaluating the effect of pharmacological substances on mucociliary activity in vivo

A test model for in vivo studies of the effect of pharmacological substances on mucociliary activity in the rabbit maxillary sinus is presented. The method permits administration of pharmacological substances and recording of the mucociliary activity under conditions that mimic the physiological situation very closely. The test substances are given intra-arterially. Using a photoelectric technique the mucociliary activity is recorded from a small and limited area of the mucous membrane. There is minimal exposure to external stimuli since normal sinus ventilation is retained. Various factors which may influence the results, e.g. the anesthesia, movements from cardiac and respiratory activity, and the volumes and injection velocities of test doses, are analysed and discussed. When the animal model was tested with serotonin, ATP, and certain cholinergic and adrenergic agents, it was found to be reliable. It permitted easy detection of changes in the mucociliary activity and gave reproducible results.

Intra- and extracellular activity of ciliated cells

A method permitting simultaneous recording in vitro of the intracellular and extracellular ( = mucociliary) activity of respiratory ciliated mucous membrane is presented. Using this method the influence of different temperature levels (20 degrees, 30 degrees, 40 degrees C) upon the tracheal mucous membrane of 15 rabbits has been investigated. It is shown 1) that the extracellular ( = mucociliary) activity increases with rising temperatures whereas the intracellular activity is unaffected and remains constant, indicating a temperature influence upon the respiratory tract mucus rather than a change of the intracellular "pace-maker" mechanism; 2) that the restraining effect of the mucus decreases with rising temperatures but is still 10% of the intracellular frequency at body temperature; 3) that the presented method should be useful for future investigations concerning the effect of air-pollution and pharmacological substances upon respiratory mucous membranes.