Biomedical subjects

I T Nathanson

Publications and source records attributed to I T Nathanson.

13 recordsLinked to original sources

PubMed1986

Structural changes associated with fluid absorption by dog tracheal epithelium.

During fluid absorption induced by amphotericin B, the lateral intercellular spaces (LIS) of the dog tracheal epithelium were widely dilated as compared to untreated time controls. When fluid absorption was inhibited by ouabain, or by replacement of luminal Na by choline, amphotericin B failed to cause dilation of the LIS. These data suggest that, as in other epithelia, a significant amount of transepithelial fluid flow passes down the LIS, and that these spaces may provide the local osmotic compartment which is responsible for linking transepithelial fluid movement to active ion transport.

Absorption↗

PubMed1983

Effects of "loop" diuretics on ion transport by dog tracheal epithelium.

The "loop" diuretics MK-196, bumetanide, piretanide, and furosemide are all potent inhibitors of Cl transport by the dog's tracheal epithelium. In short-circuited tissues, the drugs caused significant decreases in both unidirectional Cl fluxes and in the net flux of Cl toward the lumen; the change in net Cl flux was not significantly different from the change in short-circuit current. The drugs had no effect on active Na absorption. All drugs caused a significant fall in tissue conductance. All drugs, except MK-196, were more potent from the serosal bath; MK-196 was equipotent from either side of the tissue. In experiments with isolated cells, the diuretics caused no significant changes in intracellular Na and K concentrations, a fall in intracellular Cl concentration, and approximately equal falls in Na and Cl influxes. These results suggest that the site of action of these drugs is on a basolateral linked Na-Cl entry process. Additional evidence for such a linked entry process was provided by experiments in which removal of Cl reduced Na influx and removal of Na reduced Cl influx.

Animals↗

PubMed1982

Exercise tolerance and cardiorespiratory adjustments at peak work capacity in cystic fibrosis.

Exercise tolerance and cardiorespiratory adjustments at peak work capacity (PWC) were determined in 20 patients with cystic fibrosis (CF) during progressive cycle ergometry. The results were related to resting lung function tests, expressed by a pulmonary function score (PFS) that ranged from 0 (no pulmonary dysfunction) to 18 (extreme dysfunction). Patients with CF with no (PFS less than 3), mild (PFS 3-7), or moderate (PFS 8-12) pulmonary dysfunction exercised as well as normal subjects. When the PFS exceeded 12, PWC was reduced on the average by 51%, peak heart rate (PHR) was reduced by 15%, and peak ventilation (PVE) was reduced by 39%. Severely affected patients developed arterial desaturation at PWC (-7.3%), CO2 retention (end-tidal PCO2 + 5 mmHg), and an increase in the PHR/PWC ratio. In most patients with CF the PVE/PWC ratio was elevated, suggestion wasted VE and a probable increase in dead space ventilation. The results indicate that whenever pulmonary disease in CF is advanced, there are decreases in exercise tolerance and cardiorespiratory reserves, exercise-induced ventilation-perfusion abnormalities, arterial desaturation, and alveolar hypoventilation. In view of the abnormal physiological adaptations to exercise in patients with CF with advanced lung disease (PFS greater than 12), they should engage in exercise training programs and strenuous physical activity with caution and only after their cardiorespiratory reserves and adjustments to exercise have been objectively evaluated.

Adolescent↗

PubMed1973