Micropuncture study of urea excretion in parotid saliva of the rat

Mangos, J. A.; McSherry, NR

doi:10.1152/ajplegacy.1970.218.5.1329

Cited by 22 publications

(16 citation statements)

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“…Like these workers, we found that the concentration in parotid saliva is slightly but significantly less than that of plasma, an observation which has also been made in the dog (Burgen & Seeman, 1958) and rat (Mangos & McSherry, 1970).…”

Section: Discussionsupporting

confidence: 88%

The Origin and Fate of Salivary Urea and Ammonia in Man

Kopstein

Wrong

1977

Clinical Science

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1. Saliva obtained from the parotid duct of normal and uraemic subjects had an average urea concentration of 86% of the plasma concentration whereas in mixed saliva obtained from the mouth the urea concentration was only 31% of the plasma concentration. Ammonia concentrations were low or unmeasurable in parotid saliva but varied between 0.6 and 26 mmol/kg in oral saliva, showing a positive correlation with the plasma urea concentration.2. The urea in samples of mixed oral saliva incubated at 37°C disappeared by 290 min. Ammonia steadily increased during incubation; within the first 100 min, the increase could be largely accounted for by bacterial hydrolysis of urea, but later non-urea sources became relatively more important.3. These findings suggest that the ammonia in mixed oral saliva is derived by bacterial hydrolysis of urea within the mouth. However, the concentration of ammonia plus urea nitrogen in oral saliva was only 76% of the urea nitrogen concentration of parotid saliva, which suggests that some ammonia is lost from the mouth by buccal absorption or by volatilization. 4.To assess the role of non-ionic diffusion of ammonia through the buccal mucosa, we studied the effect of pH on the disappearance of ammonia from buffered solutions retained in the mouth. Ammonia concentrations fell more rapidly at pH 9 than at pH 7, as also did those of hydrazine, a non-volatile analogue of ammonia which is known to be absorbed through other mucosae by non-ionic diffusion. These findings suggest that salivary ammonia is reabsorbed passively through the oral mucosa in the un-ionized phase.

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Section: Discussionsupporting

confidence: 88%

The Origin and Fate of Salivary Urea and Ammonia in Man

Kopstein

Wrong

1977

Clinical Science

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“…This observation is in accord with the previous physiological data that the duct system is impermeable to water (Mangos and McSherry 1970;Mangos et al 1973), although other unknown AQP isoforms may be present in the ducts.…”

Section: Localization Of Aqp5supporting

confidence: 93%

Aquaporin-5 (AQP5), a water channel protein, in the rat salivary and lacrimal glands: immunolocalization and effect of secretory stimulation

Matsuzaki

Suzuki

Koyama

et al. 1999

Cell and Tissue Research

171

143

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Aquaporin-5 (AQP5) is a water channel protein and is considered to play an important role in water movement across the plasma membrane. We raised anti-AQP5 antibody and examined the localization of AQP5 protein in rat salivary and lacrimal glands by immunofluorescence microscopy. AQP5 was found in secretory acinar cells of submandibular, parotid, and sublingual glands, where it was restricted to apical membranes including intercellular secretory canaliculi. In the submandibular gland, abundant AQP5 was also found additionally at the apical membrane of intercalated duct cells. Upon stimulation by isoproterenol, apical staining for AQP5 in parotid acinar cells tended to appear as clusters of dots. These results suggest that AQP5 is one of the candidate molecules responsible for the water movement in the salivary glands.

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“…[13][14][15]In this work,observed salivary flow rates were very low(approximately 0.02 to 0.06 ml/min/kg; Table I). It was expected that in HgCl2-treated parotid saliva,urea would not be concentrated and the S/P ratios of urea should be lower than those in untreated saliva,since water reabsorption driven by reabsorption of Na+was expected to be substantially inhibited.However,the S/P ratios of urea in HgCl2-treated saliva were slightly but significantly higher than those in untreated saliva (Table III).These results suggest that urea,like Na+,is reabsorbed in the parotid striated duct of dog,and its reabsorption is inhibited by the treatment with HgCl2.It was considered that the S/P ratio of urea in untreated parotid saliva of dog might be hardly influenced by the Na+reabsorption-driven water reabsoption (Table I),but the S/P ratio might be reduced in the striated duct due to the reabsorption of urea,as well as the S/P ratio of urea in untreated mandibular saliva of dog (Table II).…”

Section: Effect Of Retrograde Injection Of Hgcl2 On S/p Ratios Of Urementioning

confidence: 56%

“…[13][14][15]In our previous studies,salivary excretion of urea as a model compound has been studied using parotid,12)mandibularsublingual,12)mandibular16.17)and sublingual16)saliva of dog.It was shown that:1)S/P ratios of urea in parotid,mandibular-sublingual,mandibular and sublingual salivas were about 0.7,0.45,0.3 and 1.25,respectively,suggesting the existence of a gland-specific difference,12'16) 2)these results on S/P ratios of urea could not be explained by Matin's equation,12)3)S/P ratios of urea in mandibular saliva are not altered during the salivary flow through the main mandibular excretory duct,16)4)urea is reabsorbed in the striated duct of mandibular gland,and this reabsorption might be inhibited by the pre-treatment of the striated duct with HgC12.17)These results suggested that the striated duct of mandibular gland might play a role in modifying the saliva concentration of urea and in the gland-specific difference of S/P ratios of urea.…”

mentioning

confidence: 99%

Difference in saliva/plasma concentration ratio of endogenous urea between mandibular and parotid glands in dogs.

Mizuno

Watanabe

Iwamoto

et al. 1988

CHEMICAL & PHARMACEUTICAL BULLETIN

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The difference in saliva/plasma concentration ratio(S/P ratio)of urea between mandibular and parotid glands in dogs was investigated in detail by a technique of retrograde ductal injection of HgC12.In every dog,four kinds of saliva[untreated(control)mandibular and parotid saliva,HgC12-treated mandibular and parotid saliva]were collected under pilocarpine stimulation of salivation. The following results were obtained.(1)It was verified in this study that S/P ratios of urea and Na+ were significantly increased in HgC12-treated mandibular saliva.(2)S/P ratios of urea and Na+in HgC12-treated parotid saliva were also significantly higher than those in untreated saliva.These results suggested that parotid salivary urea is also reabsorbed in the striated duct of dogs. (3)In untreated glands,the mean Cpr/CM ratio of urea(the ratio of urea concentration in parotid saliva to that in mandibular saliva)was about 1.65.This ratio tended to decrease toward unity in the HgC12-treated gland.Therefore,it was suggested that the striated duct might play an important role in the gland-specific difference of S/P ratios of urea between the salivary glands of dog. Keywords•\endogenous urea;salivary excretion mechanism;mandibular gland;parotid gland;striated duct;gland-specific difference;HgCl2 retrograde injection;dog Saliva levels of drugs or chemicals have been used for pharmacokinetic studies and therapeutic drug monitoring.3-6)Regarding the salivary excretion mechanism of drugs chemicals,it has been considered that most of them are excreted into saliva by a passi transport process obeying pH-partition theory(Matin's equation).7'8)In this laboratory, has been reported that the observed values of saliva/plasma concentration ratios(S/P ratic for indomethacin,9'phenobarbita1,10)5-fluorouracill 11)and urea12)do not always agree wi the estimated values according to Matin's equation,that a gland-specific difference in the S ratios is observed between parotid and mandibular-sublingual salivas of dogs,and th this difference can not be explained quantitatively by Matin's equation.Therefore,it w considered to be important to investigate the salivary excretion mechanism in detail to pern a rational assessment of the role of saliva in relation to pharmacokinetic studies al therapeutic drug monitoring.With respect to salivary excretion of endogenous or exogenous urea,other investigators have studied only parotid saliva of man,dog and rat,and reported that the mean S/P ratio was about 0.7 but varied with the salivary flow rate.13-15)In our previous studies,salivary excretion of urea as a model compound has been studied using parotid,12)mandibularsublingual,12)mandibular16.17)and sublingual16)saliva of dog.It was shown that:1)S/P ratios of urea in parotid,mandibular-sublingual,mandibular and sublingual salivas were about 0.7,0.45,0.3 and 1.25,respectively,suggesting the existence of a gland-specific difference,12'16) 2)these results on S/P ratios of urea could not be explained by Matin's equation,12)3)S/P ratios of urea in mandibular saliva are no...

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Micropuncture study of urea excretion in parotid saliva of the rat

Cited by 22 publications

References 0 publications

The Origin and Fate of Salivary Urea and Ammonia in Man

The Origin and Fate of Salivary Urea and Ammonia in Man

Aquaporin-5 (AQP5), a water channel protein, in the rat salivary and lacrimal glands: immunolocalization and effect of secretory stimulation

Difference in saliva/plasma concentration ratio of endogenous urea between mandibular and parotid glands in dogs.

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