Use of elexacaftor/tezacaftor/ivacaftor combination in pregnancy.

INTRODUCTION: Management of cystic fibrosis has recently stepped forward with the introduction of cystic fibrosis transmembrane conductance regulator (CFTR) modulators, although data on potential adverse effects are lacking for many categories of patients, such as pregnant women. METHODS: We report one of the first reports on the outcome of pregnancy in a woman treated with Elexacaftor/Tezacaftor/Ivacaftor during the second and third trimester of pregnancy, showing a significant improvement of respiratory status, compared with the first trimester when the medication was discontinued due to unknown and, therefore, potential teratogenic effects. Also, we performed the review of the existing literature on the topic. RESULTS: The course of pregnancy was uneventful, with reference to major obstetric complications, and the patient delivered a healthy neonate. These results were similar to those coming from other short series of pregnant women affected by cystic fibrosis and treated with CFTR modulators during pregnancy. CONCLUSIONS: Thus, despite the lack of evidence on the topic, the use of Elexacaftor/Tezacaftor/Ivacaftor in pregnancy seems to be apparently not associated with major adverse events, thus opening optimistic scenarios in terms of management of these patients.

Using Negative Control Outcomes and Difference-in-Differences Analysis to Estimate Treatment Effects in an Entirely Treated Cohort: The Effect of Ivacaftor in Cystic Fibrosis.

When an entire cohort of patients receives a treatment, it is difficult to estimate the treatment effect in the treated because there are no directly comparable untreated patients. Attempts can be made to find a suitable control group (e.g., historical controls), but underlying differences between the treated and untreated can result in bias. Here we show how negative control outcomes combined with difference-in-differences analysis can be used to assess bias in treatment effect estimates and obtain unbiased estimates under certain assumptions. Causal diagrams and potential outcomes are used to explain the methods and assumptions. We apply the methods to UK Cystic Fibrosis Registry data to investigate the effect of ivacaftor, introduced in 2012 for a subset of the cystic fibrosis population with a particular genotype, on lung function and annual rate (days/year) of receiving intravenous (IV) antibiotics (i.e., IV days). We consider 2 negative control outcomes: outcomes measured in the pre-ivacaftor period and outcomes among persons ineligible for ivacaftor because of their genotype. Ivacaftor was found to improve lung function in year 1 (an approximately 6.5-percentage-point increase in ppFEV1), was associated with reduced lung function decline (an approximately 0.5-percentage-point decrease in annual ppFEV1 decline, though confidence intervals included 0), and reduced the annual rate of IV days (approximately 60% over 3 years).

[Improving the management of chronic Pseudomonas aeruginosa infection in lower respiratory tract].

Pseudomonas aeruginosa is one of the most important pathogens causing chronic lower respiratory tract infections in patients with chronic lung diseases such as cystic fibrosis, bronchiectasis and chronic obstructive pulmonary disease. The poor prognosis of these diseases has been found to be associated with chronic Pseudomonas aeruginosa infection in lower respiratory tract, which can be a consequence or a cause of the disease progression depending on different circumstances. Optimizing the management of chronic Pseudomonas aeruginosa infection is of great significance to improve the prognosis of these chronic lung diseases. Unlike the therapy of acute pneumonia due to Pseudomonas aeruginosa, the goals of the management for chronic Pseudomonas aeruginosa infection are not only to control infection, but also to reduce symptoms, prevent exacerbations, stop the disease progression and improve the quality of life. In addition to systemic anti-pseudomonas therapy during exacerbations, long-term multiple measures including anti-inflammatory therapy, immunomodulatory therapy,airway clearance techniques, mucoactive therapy, etc. should also be given to the patients with chronic lower respiratory tract infection due to Pseudomonas aeruginosa.

Acid exposure disrupts mucus secretion and impairs mucociliary transport in neonatal piglet airways.

Tenacious mucus produced by tracheal and bronchial submucosal glands is a defining feature of several airway diseases, including cystic fibrosis (CF). Airway acidification as a driving force of CF airway pathology has been controversial. Here we tested the hypothesis that transient airway acidification produces pathologic mucus and impairs mucociliary transport. We studied pigs challenged with intra-airway acid. Acid had a minimal effect on mucus properties under basal conditions. However, cholinergic stimulation in acid-challenged pigs revealed retention of mucin 5B (MUC5B) in the submucosal glands, decreased concentrations of MUC5B in the lung lavage fluid, and airway obstruction. To more closely mimic a CF-like environment, we also examined mucus secretion and transport following cholinergic stimulation under diminished bicarbonate and chloride transport conditions ex vivo. Under these conditions, airways from acid-challenged pigs displayed extensive mucus films and decreased mucociliary transport. Pretreatment with diminazene aceturate, a small molecule with ability to inhibit acid detection through blockade of the acid-sensing ion channel (ASIC) at the doses provided, did not prevent acid-induced pathologic mucus or transport defects but did mitigate airway obstruction. These findings suggest that transient airway acidification early in life has significant impacts on mucus secretion and transport properties. Furthermore, they highlight diminazene aceturate as an agent that might be beneficial in alleviating airway obstruction.

Safety and Pharmacokinetics Following Oral or Intravenous Lefamulin in Adults With Cystic Fibrosis.

PURPOSE: Methicillin-resistant Staphylococcus aureus infections are increasing in prevalence in patients with cystic fibrosis (CF) and are associated with worsening lung function and increased mortality. Lefamulin is a pleuromutilin antimicrobial approved to treat community-acquired bacterial pneumonia based on potent in vitro activity and clinical efficacy. This Phase I, open-label, randomized crossover study assessed the safety and pharmacokinetic profile of oral and intravenous (IV) lefamulin in adults with CF. METHODS: The study comprised 2 dosing periods in which adults with CF (N = 13) received a single dose of lefamulin via a 150-mg IV infusion or 600-mg immediate-release orally administered tablet, separated by a 4- to 7-day washout period. Pharmacokinetic and safety parameters were assessed after lefamulin treatment. FINDINGS: Single doses of lefamulin administered via oral tablet or IV infusion resulted in comparable drug exposure, and sputum analysis suggested rapid penetration of lefamulin into the lung. Comparison of the present results with those obtained from prior single-dose studies of healthy volunteers indicate no meaningful difference in the pharmacokinetic properties of lefamulin in patients with CF. Treatment-emergent adverse events were consistent with previous reports, and the majority were mild in severity. IMPLICATIONS: These results show similar lefamulin pharmacokinetic and safety profiles between patients with CF and healthy volunteers receiving the same oral and IV doses, suggesting no need for lefamulin dose adjustment in patients with CF and indicating the potential of lefamulin as therapy for lung infections in patients with CF. CLINICALTRIALS: gov identifier: NCT05225805.

Tobramycin and vestibulotoxicity: retrospective analysis of four cases.

Over a course of 7 months, four patients developed vestibulotoxicity after treatment with intravenous tobramycin. Since vestibulotoxicity is a serious adverse effect which can be irreversible, an investigation was undertaken to determine if there was a cause for the toxicity and whether the quality of care had been inadequate. In this period, 26 patients with cystic fibrosis were treated with tobramycin according to valid guidelines, of which four experienced acute dizziness which disrupted their daily activities. Two patients experienced irreversible bilateral vestibular hypofunction and two unilateral loss of the right labyrinth, with decreasing dizziness over time. No apparent cause for the vestibulotoxicity was found in these four patients and the simultaneous occurrence was not due to a lack in quality of care. Symptoms of dizziness and balance disorders should be recognised by patients and caretakers at an early stage so additional diagnostics can be done to prevent further deterioration.

Phase 1 Study to Assess the Safety and Pharmacokinetics of Elexacaftor/Tezacaftor/Ivacaftor in Subjects Without Cystic Fibrosis With Moderate Hepatic Impairment.

BACKGROUND AND OBJECTIVE: Elexacaftor/tezacaftor/ivacaftor is highly effective in treating people with cystic fibrosis (pwCF) who have ≥ 1 responsive mutation. Liver disease occurs in approximately 10%-20% of pwCF. The objective of this study was to assess the safety and pharmacokinetics of elexacaftor/tezacaftor/ivacaftor in people with moderate hepatic impairment, which is necessary to inform on its use and guide dosing recommendations. METHODS: The safety and pharmacokinetics of elexacaftor/tezacaftor/ivacaftor were evaluated in subjects without CF with moderate hepatic impairment versus matched healthy controls. Twenty-two subjects (11 with moderate hepatic impairment and 11 healthy subjects) received half the standard adult daily dose of elexacaftor/tezacaftor/ivacaftor (elexacaftor 100 mg/tezacaftor 50 mg/ivacaftor 150 mg) orally for 10 days. RESULTS: Elexacaftor/tezacaftor/ivacaftor was safe and well tolerated in subjects with moderate hepatic impairment and healthy controls. On day 10, the mean values of the area under the curve during the dosing interval (AUCτ) for total (bound and unbound) elexacaftor and its major active metabolite M23-elexacaftor were increased 1.25-fold (95% CI 1.01, 1.54) and 1.73-fold (95% CI 1.27, 2.35), respectively, in subjects with moderate hepatic impairment compared with matched healthy subjects. The mean values of AUCτ for ivacaftor and tezacaftor were increased 1.50-fold (95% CI 1.09, 2.06) and 1.20-fold (95% CI 1.00, 1.43), respectively, while the mean value of AUCτ for the active metabolite M1-tezacaftor was 1.29-fold lower [ratio of moderate hepatic impairment to healthy subjects (95% CI): 0.778 (0.655, 0.924)] in subjects with moderate hepatic impairment. CONCLUSIONS: A dose reduction of elexacaftor/tezacaftor/ivacaftor is warranted in people with moderate hepatic impairment. (Trial registry number 2018-002570-40; registered 2 July 2018.).

Elexacaftor/tezacaftor/ivacaftor is a combination product (made up of the three drugs elexacaftor, tezacaftor, and ivacaftor) that can effectively treat cystic fibrosis (CF). About 10%­20% of people with CF have liver disease, and the liver plays an important role in breaking down these drugs. Thus, it is important to understand how liver disease or reduced liver function affects the amounts of these drugs in the body over time. This can help determine how much of the drug (i.e., what dose) people should take.We gave people with reduced liver function and healthy people (with normal liver function) elexacaftor/tezacaftor/ivacaftor for 10 days. We looked at the safety of the combination and measured the amounts of elexacaftor, tezacaftor, and ivacaftor in the body over time.We found that when people with moderately reduced liver function take elexacaftor/tezacaftor/ivacaftor, they have higher amounts of the drugs elexacaftor, tezacaftor, and ivacaftor in their bodies compared with healthy people with normal liver function. These findings mean that people with moderately reduced liver function should take a lower dose of elexacaftor/tezacaftor/ivacaftor.

[Genetic revision of the Hungarian Cystic Fibrosis Registry]. / A magyar Cystás Fibrosis Regiszter genetikai revíziója.

INTRODUCTION: Cystic fibrosis (CF) is one of the most common monogenic diseases. Genetic testing is becoming increasingly reasoned to establish or confirm the diagnosis by detecting abnormal mutations. OBJECTIVE: In order to develop a diagnostic strategy for cystic fibrosis and to facilitate mutation-specific treatments, the genetic revision of the Hungarian Cystic Fibrosis Registry was performed. METHOD: 582 patients' data and samples were used for the revision (528 originally included in the register and 54 received during the revision). First we reviewed the patients' existing genetic findings. Wherever necessary, a comprehensive three-level genetic analysis of the CFTR gene was done. RESULTS: According to our study, of the 528 patients present in the Registry, 395 (74.8%) had 2 pathogenic CFTR mutations. We completed and corrected 94 patients' previously incomplete genetic status. 73 different pathogenic variants were described, in which 1 aberration was not previously reported (c.3130G>A). The 5 most common mutations were: F508del (68.4%); CFTRdele2,3 (3.7%); G542X (3.2%); 2184insA (2.7%); W1282X (2.3%). Based on genotype and age, in Hungary 211 patients are eligible for the available lumacaftor-ivacaftor combination therapy, and 361 patients for the ivacaftor-tezacaftor-elexacaftor therapy. CONCLUSION: Due to the revision, we could identify the patients who can benefit from mutation-specific drugs instead of symptomatic therapy. In addition, the data obtained have been used to map the Hungarian distribution of mutations in the CFTR gene, which will help to develop a diagnostic strategy. Orv Hetil. 2022; 163(51): 2052-2059.

Short-term CFTR inhibition reduces islet area in C57BL/6 mice.

Cystic fibrosis-related diabetes (CFRD) worsens CF lung disease leading to early mortality. Loss of beta cell area, even without overt diabetes or pancreatitis is consistently observed. We investigated whether short-term CFTR inhibition was sufficient to impact islet morphology and function in otherwise healthy mice. CFTR was inhibited in C57BL/6 mice via 8-day intraperitoneal injection of CFTRinh172. Animals had a 7-day washout period before measures of hormone concentration or islet function were performed. Short-term CFTR inhibition increased blood glucose concentrations over the course of the study. However, glucose tolerance remained normal without insulin resistance. CFTR inhibition caused marked reductions in islet size and in beta cell and non-beta cell area within the islet, which resulted from loss of islet cell size rather than islet cell number. Significant reductions in plasma insulin concentrations and pancreatic insulin content were also observed in CFTR-inhibited animals. Temporary CFTR inhibition had little long-term impact on glucose-stimulated, or GLP-1 potentiated insulin secretion. CFTR inhibition has a rapid impact on islet area and insulin concentrations. However, islet cell number is maintained and insulin secretion is unaffected suggesting that early administration of therapies aimed at sustaining beta cell mass may be useful in slowing the onset of CFRD.

Acidic pH increases airway surface liquid viscosity in cystic fibrosis.

Cystic fibrosis (CF) disrupts respiratory host defenses, allowing bacterial infection, inflammation, and mucus accumulation to progressively destroy the lungs. Our previous studies revealed that mucus with abnormal behavior impaired mucociliary transport in newborn CF piglets prior to the onset of secondary manifestations. To further investigate mucus abnormalities, here we studied airway surface liquid (ASL) collected from newborn piglets and ASL on cultured airway epithelia. Fluorescence recovery after photobleaching revealed that the viscosity of CF ASL was increased relative to that of non-CF ASL. CF ASL had a reduced pH, which was necessary and sufficient for genotype-dependent viscosity differences. The increased viscosity of CF ASL was not explained by pH-independent changes in HCO3- concentration, altered glycosylation, additional pH-induced disulfide bond formation, increased percentage of nonvolatile material, or increased sulfation. Treating acidic ASL with hypertonic saline or heparin largely reversed the increased viscosity, suggesting that acidic pH influences mucin electrostatic interactions. These findings link loss of cystic fibrosis transmembrane conductance regulator-dependent alkalinization to abnormal CF ASL. In addition, we found that increasing Ca2+ concentrations elevated ASL viscosity, in part, independently of pH. The results suggest that increasing pH, reducing Ca2+ concentration, and/or altering electrostatic interactions in ASL might benefit early CF.

Alterations of amylase secretion in the chronically reserpinized rat: an acetylcholine-mediated phenomenon.

Chronic reserpine treatment of animals, an experimental model for cystic fibrosis (CF), results in generalized exocrinopathy, impaired secretion, and decreased pancreatic content of amylase. However, the mechanisms of altered acinar pancreatic function in both CF patients and reserpine-treated rats are still unknown. The present study was designed to investigate the secretory response of the rat pancreas after reserpine treatment. Rats were given reserpine (1 mg kg-1 day-1 ip) or vehicle, and killed 2, 4, or 7 days later. To distinguish between specific effects of reserpine and those related to secondary malnutrition caused by the drug, secretory response of a group of pair-fed animals to reserpine was also investigated. During reserpine treatment, body weight and food intake were significantly reduced from the 2nd day on. Amylase release from dispersed pancreatic acini, prepared from control pair-fed and from reserpine-treated rats were used to evaluate functional secretory capacity. After 7 days, both chronic reserpine and pair-feeding significantly decreased pancreatic amylase concentration to 75 and 50% of controls, respectively. Reserpine caused desensitization of the pancreatic acini secretory response to carbamylcholine, without altering maximal amylase release. Desensitization occurred gradually and reached a maximum after 7 days. Secretory responses to caerulein and to the phorbol ester 12.0-tetradecanoyl phorbol-13 acetate (TPA) were not altered. These findings indicate that desensitization of amylase release after reserpine was specific to this muscarinic agonist. It may result from increased endogenous acetylcholine release in the course of treatment.

A novel orally active inhibitor of HLE.

Human leukocyte elastase (HLE) is a serine proteinase, capable of degrading a variety of structural matrix proteins. SSR69071 2-[(4-isopropyl-6-methoxy-1,1-dioxido-3-oxo-1,2-benzisothiazol-2(3H)-yl)methoxy]-9-(2-piperidin-1-ylethoxy)-4H-pyrido[1,2-a]pyrimidin-4-one was selected as a novel orally active HLE inhibitor for treatment of chronic obstructive pulmonary diseases, asthma, emphysema, cystic fibrosis and several inflammatory diseases (WO 01/44245 A1) (J. Pharm. Exp. Ther., submitted for publication).

Effects of chronic and in utero treatment with diuretics on mouse exocrine cells studied by X-ray microanalysis.

In an attempt to develop an animal model for the disease cystic fibrosis, mice were chronically treated with diuretics. In addition, pregnant mice were treated with diuretics and the effect of this treatment in utero on the newborn mice was studied. Pancreas and submandibular gland acinar cells were investigated by X-ray microanalysis and transmission electron microscopy. Long-term treatment with furosemide (up to 13 months) caused transient changes in the elemental content of the pancreatic acinar cells: a decrease in chloride and sulfur, and an increase in phosphorus, potassium and magnesium. All changes normalized with prolonged treatment. Some morphological changes were found in the zymogen granules. Treatment with amiloride or furosemide in utero caused a decrease in cellular sodium and chloride levels, indicative of inhibition of transepithelial ion and fluid transport. Also treatment of adult animals for two months with amiloride caused lower intracellular sodium and chloride levels. In adult animals only minor effects of diuretic treatment on submandibular gland acinar cells were noted. In utero treatment with amiloride caused an increase in sodium and chloride content indicative of cell damage.

Impairment of pancreatic acinar function by reserpine in vivo and in vitro.

Chronic reserpine treatment of animals, an experimental model for cystic fibrosis (CF), results in generalized exocrinopathy, impaired pancreatic secretion, and decreased pancreatic content of amylase. The mechanisms of altered acinar function and decreased amylase content in both CF and the reserpine-treated rat are unknown. To examine this alteration, the rate of [3H]phenylalanine (phe) incorporation into cellular protein was determined in pancreatic acinar cells after reserpine treatment of rats in vivo (7 d) and of cells in vitro (1 to 24 h). Acinar cells isolated from control, chronic reserpine-treated, and pair-fed rats were incubated in vitro with 0, 30, 50, or 100 microM reserpine. Reserpine treatment in vitro for 24 h of acinar cells from control rats significantly decreased amylase activity (20 to 70%), an effect similar to that of reserpine treatment in vivo. In vivo, reserpine treatment decreased [3H]phe incorporation (disintegrations per minute per milligram protein) 56% in freshly isolated cells, but did not alter intracellular specific activity (disintegrations per minute per nanomole phe, SA) of [3H]phe. Reserpine treatment (30 and 50 microM) in vitro for 1 h also decreased [3H]phe incorporation by freshly isolated cells from control (53 to 85%) and pair-fed (40 to 68%) rats. Reserpine treatment for 24 h in vitro significantly decreased [3H]phe incorporation by cells from control (82 and 98%), pair-fed (80 and 95%), and chronic reserpine-treated (90 and 97%) rats as compared with cells from respective in vivo treatments cultured with no reserpine. In vitro reserpine treatment also decreased the intracellular SA of [3H]phe in freshly isolated cells from control (14 and 36%) and pair-fed (35 and 39%) rats and in cultured cells from control (11 and 86%), pair-fed (60 and 88%), and chronic reserpine-treated (49 and 76%) rats. However, these alterations of SA by reserpine did not account for the decreased incorporation of [3H]phe into acinar protein, which remained significantly lower (70 to 88%) when expressed as total phe incorporation. These results suggest that reserpine acts directly on acinar cells to alter function and that the ability of the pancreas to synthesize digestive enzymes may be impaired in this model of cystic fibrosis.

Acute and chronic models for hypersecretion of intestinal mucin.

Mucin secretion was examined in three functional models relevant to human disease, using rat small intestinal rings or in situ loops, [3H]glucosamine precursor labelling, gel chromatography and a specific radioimmunoassay for mucin. As a model for acute bacterial secretory diarrhoea, tissues were exposed to cholera toxin for up to 4 h. Both stored and newly synthesized radioactive glycoproteins were secreted in amounts twofold to threefold above control levels. Immunoreactive mucin secretion increased fivefold to eightfold. Other agents known to raise cAMP levels did not stimulate mucin secretion, suggesting that cholera may release mucin by a non-cAMP-dependent mechanism. Sepharose 2B chromatography indicated that secreted mucin was smaller in size than intracellular mucin and had compositional differences suggestive of 'immaturity' or protein contamination. In chronically (seven days) reserpinized rats, used as a model of glycoprotein abnormalities relevant to cystic fibrosis, mucin secretion increased twofold to threefold, but the most prominent abnormality was a marked increase in [3H]glucosamine incorporation into all tissue glycoproteins. On purification, the intracellular mucin of reserpine-treated rats had the same composition as mucin from control rats, but the former was smaller in size and had a higher specific radioactivity. Mucin hypersecretion in reserpinized rats may therefore be secondary to a primary and chronic hyperstimulation of mucin biosynthesis. A model of intestinal 'anaphylaxis' or immune-mediated diarrhoea was created in Hooded Lister rats by immunizing with egg albumin (10 micrograms) and challenging with the same antigen in intestinal loops 14 days later. After 4 h, total protein, DNA and brush border sucrase were increased in the lumen. Enhancement of mucin secretion did not occur, however, and therefore does not seem to be a particular feature of the pathophysiology of this model.

Morphological and histochemical changes in intestinal mucosa in the reserpine-treated rat model of cystic fibrosis.

The present investigation was undertaken to determine whether or not there are histochemical and morphological changes in the intestine of the chronically reserpine-treated rat, an animal model of cystic fibrosis. Male Sprague-Dawley rats were given seven daily intraperitoneal injections of reserpine at dosages of 0.5 (n = 6) or 1.0 mg/kg body weight (n = 6). Control groups consisted of parfed solvent-injected (n = 6), solvent-injected (n = 4), and saline-injected animals (n = 4). Light microscopic histochemical procedures and morphological assessments were performed on sections of "Swiss rolls" of small and large intestine. Chronic reserpine treatment caused an increase in the sulfation of goblet cell mucin in the small intestine without accompanying morphological change; these findings resemble those reported in cystic fibrosis. No qualitative differences in mucin were found in the large intestine but there was an increased number of goblet cells in the surface epithelium and retention of mucus within these cells. Similar although less marked changes were noted in the parfed controls suggesting that those observed in the treated groups may be due, in part, to the reserpine-induced anorexia. The resemblance between the changes in the small intestine of the reserpine-treated rat and those observed in CF patients supports the contention that the chronically reserpine-treated rat is suitable as a model of cystic fibrosis.

The chronically reserpinized rat as a possible animal model for cystic fibrosis. IV. The protein composition of pulmonary lavage fluid.

Lung lavage samples obtained from patients with cystic fibrosis (CF) had significantly higher levels of total protein per ml lavage fluid (0.49 vs. 0.30 mg/ml). A significant increase in the absolute and relative amounts of a low molecular weight glycoprotein (15,000 mol wt) was noted in lavage specimens from CF patients. Reserpine-treated rats also showed a significant increase in the total protein recovered in the lung lavage fluid with a 233% increase in the absolute and relative amounts of a low molecular weight glycoprotein (15,000 mol wt). Thus, reserpine induced changes in the secretions of the lung of the rat which are similar to those observed in samples obtained from the lung of CF patients.

The reserpinized rat in the study of cystic fibrosis: x-ray microanalysis of submandibular gland and pancreas.

The chronically reserpinized rat has been suggested as an animal model for cystic fibrosis. X-ray microanalysis of thick and thin cryosections was carried out to assess elemental redistribution in the submandibular glands and the pancreas of reserpinized rats at the cellular and subcellular level. In the submandibular gland of reserpinized rats, calcium and magnesium concentrations were significantly elevated. Mucus globules, secretory granules, and endoplasmic reticulum were the primary sites of the localization of excess calcium and magnesium. A significant potassium loss from the gland had occurred, particularly from the serous cells. Electron microscopy of conventionally prepared tissue showed marked swelling of the endoplasmic reticulum, especially in mucous cells. The elemental changes in the pancreatic acinar cells of reserpinized rats were reminiscent of elemental redistribution connected with cell death: increased levels of sodium, chlorine, and calcium and decreased levels of magnesium and potassium. Ultrastructural changes included swelling of the endoplasmic reticulum and obstruction of the acinar lumen. It is concluded tha elemental redistribution in chronically reserpinized rats presents interesting parallels with cystic fibrosis.

Chronically reserpinized rat as a model for cystic fibrosis: Na+ transport inhibitory effect in submaxillary saliva.

The retrograde perfusion assay in the rat parotid gland was used to investigate the effects of salivary secretions from control and reserpine-treated rats on Na+ reabsorption. Results demonstrated that submaxillary saliva from the treated animals caused a 69% inhibition of Na+ reabsorption, accompanied by a 28% reduction in the volume of saliva secreted, and a 22% reduction in flow rate. By contrast, submaxillary saliva from control rats caused a 6% inhibition of Na+ reabsorption, a 6% reduction in volume, and a 5% reduction in flow rate. Parotid saliva from reserpine-treated rats also inhibited Na+ reabsorption to the extent of 39% and caused a 38% reduction in volume and a 33% reduction in flow. Parotid saliva from control rats only inhibited Na+ reabsorption to the extent of 2.7% and caused a 4--6% reduction in salivary volumes and flow rates. The inhibition of Na+ reabsorption and the reduction in salivary volume and flow rates caused by submaxillary saliva of reserpine-treated rats were either abolished or significantly reduced when the saliva was previously heated to 100 degrees C, frozen, and then thawed or kept in glass tubes at 4 degrees C for 24 hr. These results indicate that saliva from reserpine-treated rats have comparable effects in this assay system to those of saliva from cystic fibrosis (CF) patients and further support its use as an animal model for this disease.