Endogenous chloride channels of insect sf9 cells. Evidence for coordinated activity of small elementary channel units.

The endogenous Cl- conductance of Spodoptera frugiperda (Sf9) cells was studied 20-35 h after plating out of either uninfected cells or cells infected by a baculovirus vector carrying the cloned beta-galactosidase gene (beta-Gal cells). With the cation Tris+ in the pipette and Na+ in the bath, the reversal potential of whole-cell currents was governed by the prevailing Cl- equilibrium potential and could be fitted by the Goldman-Hodgkin-Katz equation with similar permeabilities for uninfected and beta-Gal cells. In the frequency range 0.

Mechanism of sodium hyperabsorption in cultured cystic fibrosis nasal epithelium: a patch-clamp study.

Transepithelial Na+ absorption is increased two to three times in cystic fibrosis (CF) compared with normal (NL) airway epithelia. This increase has been associated with a higher Na+ permeability of the apical membrane of airway epithelial cells. Because Na+ absorption is electrogenic and abolished by amiloride, Na+ channels are thought to dominate the apical membrane Na+ permeability.

Sodium-permeable channels in the apical membrane of human nasal epithelial cells.

We used patch-clamp techniques to study the channels that underlie the Na+ conductance of the apical membrane of human normal nasal epithelial cells. Cells were cultured on permeable supports and studied after confluence. In 172 of 334 (52%) excised membrane patches, we observed 20-pS Na(+)-permeable channels that do not discriminate between Na+ and K+ (pNa/pK = 1.

Regulation of Cl- channels in normal and cystic fibrosis airway epithelial cells by extracellular ATP.

The rate of Cl- secretion by human airway epithelium is determined, in part, by apical cell membrane Cl- conductance. In cystic fibrosis airway epithelia, defective regulation of Cl- conductance decreases the capability to secrete Cl-. Here we report that extracytosolic ATP in the luminal bath of cultured human airway epithelia increased transepithelial Cl- secretion and apical membrane Cl- permeability.

Acute cardiovascular and pulmonary effects of intravenous and aerosolized amiloride in the dog.

Active Na+ absorption by the epithelia that line the airways can drive volume from the airway surface. Exposure of the lumen-facing surface of airway epithelia to amiloride inhibits Na+ transport. Consequently, aerosolized amiloride may help hydrate the desiccated surface liquid that characterizes lung diseases such as cystic fibrosis.

Frequency dependence of effective nasal resistance.

Forced random noise techniques were used to characterize the effective resistance of the nasal passages in normal subjects and subjects who were candidates for surgical correction of nasal obstruction. The slope of the effective resistance curve was characterized by the average resistances over 3 to 5 Hz and 13 to 15 Hz. Subjects with nasal obstruction had effective nasal resistance curves which were more frequency-dependent than those of normal subjects (p less than 0.

Pulmonary impedance in dogs measured by forced random noise with a retrograde catheter.

Retrograde catheter and forced random noise techniques were combined to study the distribution of resistance and compliance in dogs following the inhalation of aerosols containing 2.5 and 5.0 mg/ml of histamine.

Correlation of airway resistance with forced random noise resistance parameters.

The correlation between airway resistance (Raw) measured in a plethysmograph and three respiratory resistance parameters measured by forced random noise was evaluated. Forced random noise resistance parameters were the average resistance between 5 and 9 hz (R5-9), the average resistance between 20 and 24 Hz (R20-24), and the extrapolated resistance at 1 Hz (R1). We studied 22 healthy, nonsmoking subjects, 10 of whom had a history suggesting childhood asthma.

Detection of respiratory mechanical dysfunction by forced random noise impedance parameters.

Respiratory mechanical parameters were computed from forced random noise impedance data in normal adults (group 1), asymptomatic smokers (group 2), and patients with obstructive pulmonary disease (group 3). Mean values for all derived parameters were significantly different (p less than 0.025) for group 3.

Fractionating respiratory resistance in young children.

Total respiratory resistance (Rrs) and the fraction of this resistance located peripherally, (Fp) were measured in a group of children (3--5 yr old). The technique used forced random noise to characterize the frequency dependence of effective resistance and an algorithm to compute Rrs and Fp from these data. The overall mean value +/- SD for Fp was 0.

Respiratory impedance and derived parameters in young children by forced random noise.

The frequency dependence of total respiratory impedance during spontaneous breathing was measured repeatedly in 16 children (3--5 yr old) over a 3-mo period using forced random noise and spectral analysis. Total respiratory resistance, compliance, and inertance, which were calculated fromthe impedance data using regression analysis with a second-order model, had overall mean values +/- SD of 5.61 +/- 0.