Standardized Assay for the Sodium Reabsorption Inhibitory Effect and Studies of Its Salivary Gland Distribution in Patients with Cystic Fibrosis

Abstract

ExtractThe retrograde perfusion assay of Mangos for the sodium reabsorption inhibitory effect in sweat and mixed saliva from patients with cystic fibrosis (CF) was modified by (I) using the second parotid gland of the rat as a control, (2) carefully controlling the quantity of saliva perfused into the rat parotid gland so that the ratio of milliliters perfused to gram dry gland weight fell between 1.8 and 2.8, and (3) reporting the inhibitory effect as percentage of inhibition of the rate of sodium reabsorption (RNa) in the perfused gland calculated from the difference between the RNals in the two glands. Using this modified assay we were able to confirm that significant differences exist in the percentage of inhibition of RNa caused by CF and normal mixed saliva (47.0 f 24.8 and 18.0 -1. 8.3, mean f SD). In addition, similar significant differences in the percentage ' of inhibition of R~~ by submandibular gland secretions (39.7 f 13.5 and 16.0 f 11.8). sublinrrual dand secretions (39.5 f 6.0 and 19.7 + 14.3), and'submu~osal gland secretions (34.0 f 11.7 and 21.7 f 12.7) between CF and normal subjects were observed. However, parotid gland secretions from CF subiects showed no increased inhibitory effect (12.5 + 7.9 and" 12.5 f 6.6). These findings demonstrate, that the sodium reabsorption inhibitory effect is produced by the secretions from some but not all salivary glands of patients with CF. SpeculationThese results indicate that the substance or substances responsible for the sodium reabsorption inhibitory effect of CF secretions is produced by cells present in submandibular, sublingual, and submucosal glands of patients with CF. Because mucus-producing cells are abundant in submandibular, sublingual, and submucosal glands, but are sparse in parotid glands (1) we suggest, as have Johansen e t al. (4), that the inhibitory effect is in some way related to the mucous secretory product of the cystic fibrosis glands.Cystic fibrosis is an inherited disease involving the exocrine glands. The most consistent finding in this disease is that of elevated concentrations of chloride and sodium in sweat (2) and secretions of the minor salivary glands (14). The pathophysiology of this alteration has not been clearly defined. Mangos e t al. (12) and Mangos and McSherry (10) have shown that retrograde perfused CF sweat and saliva inhibit sodium reabsorption in the ducts of the rat parotid glands. Studies by Kaiser e t al. (5) also show that sweat from CF patients causes inhibition of sodium reabsorption when it is perfused into normal human sweat gland ducts. A specific sodium reabsorption inhibitory factor (5, 10-12) may be the cause of the elevated sodium concentrations found in these secretions; however, such a factor has not been identified.The sodium reabsorption inhibitory effect in rat parotid gland ducts has not been reproduced by other laboratories. Using a modification of the Mangos technique we now have been able to demonstrate a sodium reabsorption inhibitory effect in mixed saliva of patients with CF. Further wor...

Cystic Fibrosis Factors. Effect of Serum on the Secretory Response of Dispersed Rat Submandibular Cells

“…Among the activities reported to occur in serum, saliva, or sweat from the C F patient are inhibition of ciliary movement (2,6,31), stimulation of polymorphonuclear leukocyte degranulation (S), inhibition of alveolar macrophage phagocytic activity (33), inhibition of the glycogen debranching enzyme (1 I), and interference with cation handling during the secretory process of the salivary gland (16,17,32) and the svlreat gland (13,15). The clinical presentation in the patient implies exocrine gland target specificity if these factors have a relationship to the pathophysiology of CF.…”

Apparent Absence of Cystic Fibrosis Sweat Factor on Ion-selective and Transport Properties of the Perfused Human Sweat Duct

“…Both saliva (8)(9)(10)22) and sweat (8) retroinjected into the rat parotid gland were reported to inhibit Na+ reabsorption in this tissue. An evaluation of these results is beyond the scope ofthis discussion, but it seems peculiar that these secretions should be effective in inhibiting Na+ transport in the rat parotid gland when no significant abnormalities in electrolyte content in secretions from the same organ in CF subjects has been identified (12,14), but it may not be the CF parotid gland that secretes an inhibitory substance (23).…”

“…In contrast to many of the preparations used previously to assay for the presence of inhibitory factors, particularly those requiring retroinjection, the present microperfusion system seems more direct and perhaps better controlled. For example, due to the difficulty in controlling retroinjection procedures, reproducibility of earlier work required that data be accepted only when the volume of retroinjected fluid was closely matched to gland weight (22).…”

“…It has been postulated that the abnormal electrolyte transport in the CF sweat duct is due to a transport-inhibiting substance present in CF sweat (6,11). It was further suggested that a similar inhibitory substance may be present in other exocrine secretions since saliva from CF patients was reported to inhibit electrolyte reabsorptive processes in other tissues as well (8,22,24).…”

Cystic Fibrosis: Isolation and Physical Properties of a Salivary Cystic Fibrosis Factor

“…These factors have in general been described as immunoglobulins, complement components, abnormal proteins, peptides ranging from 1,000-10,000 in molecular weight, as well as abnormal enzymes and polyamines and/or their metabolites (7, 8, 10-12, 15, 20, 22, 29, 31, 33,35). Various bioassays have been developed for the detection of these CF factors and include the oyster gill ciliary assay developed by Bowman et al (7) and modified by Schmoyer et al (39), a fresh water mussel assay by Besley et al (4), a modification of the original rabbit tracheal assay (40) described by Conover et al (9), the retrograde perfusion assay by Mangos (29)(30)(31), and its modification as described by Taylor et al (41), and recently a short-circuit current membrane system by Araki et al (1) adapted from Asano (2). In addition, a means of detection utilizing isoelectric focusing has been described by Wilson and Fudenberg (43).…”