Document Detail

Lowering of interstitial fluid pressure in rat submandibular gland: a novel mechanism in saliva secretion.
MedLine Citation:
PMID:  16284231     Owner:  NLM     Status:  MEDLINE    
The submandibular gland transports fluid at a high rate through the interstitial space during salivation, but the exact level of all forces governing transcapillary fluid transport has not been established. In this study, our aim was to measure the relation between interstitial fluid volume (V(i)) and interstitial fluid pressure (P(if)) in salivary glands during active secretion and after systemically induced passive changes in gland hydration. We tested whether interstitial fluid could be isolated by tissue centrifugation to enable measurement of interstitial fluid colloid osmotic pressure. During control conditions, V(i) averaged 0.23 ml/g wet wt (SD 0.014), with a corresponding mean P(if) measured with micropipettes of 3.0 mmHg (SD 1.3). After induction of secretion by pilocarpine, P(if) dropped by 3.8 mmHg (SD 1.5) whereas V(i) was unchanged. During dehydration and overhydration of up to 20% increase of V(i) above control, a linear relation was found between volume and pressure, resulting in a compliance (DeltaV(i)/DeltaP(if)) of 0.012 ml.g wet wt(-1).mmHg(-1). Interstitial fluid was isolated, and interstitial fluid colloid osmotic pressure averaged 10.4 mmHg (SD 1.2), which is 64% of the corresponding level in plasma. We conclude that P(if) drops during secretion and, thereby, increases the net transcapillary pressure gradient, a condition that favors fluid filtration and increases the amount of fluid available for secretion. The reduction in P(if) is most likely induced by contraction of myoepithelial cells and suggests an active and new role for these cells in salivary secretion. The relatively low interstitial compliance of the organ will enhance the effect of the myoepithelial cells on P(if) during reduced V(i).
Ellen Berggreen; Helge Wiig
Publication Detail:
Type:  In Vitro; Journal Article; Research Support, N.I.H., Extramural     Date:  2005-11-11
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  290     ISSN:  0363-6135     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-03-15     Completed Date:  2006-05-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H1460-8     Citation Subset:  IM    
Section for Physiology, Dept. of Biomedicine, University of Bergen, Norway.
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MeSH Terms
Extracellular Fluid / physiology*
Mechanotransduction, Cellular / physiology*
Rats, Wistar
Saliva / secretion*
Salivation / physiology*
Submandibular Gland / physiology*
Water-Electrolyte Balance / physiology*

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