May 2004
Volume 45, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2004
Compartmentalized Fluids Permit Adherence of Detached Rat Lacrimal Gland to its Bed
Author Affiliations & Notes
  • M. Lorber
    Physiology & Biophysics, Georgetown Univ Med School, Washington, DC
  • Footnotes
    Commercial Relationships  M. Lorber, None.
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Investigative Ophthalmology & Visual Science May 2004, Vol.45, 3865. doi:
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      M. Lorber; Compartmentalized Fluids Permit Adherence of Detached Rat Lacrimal Gland to its Bed . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3865.

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Abstract

Abstract: : Purpose: From a previous study (Lorber, Adv Exp Med Biol 438:75, 1998) it was recalled that despite removal of all attachments the rat exorbital lacrimal gland adhered to its bed. This study sought to ascertain the role of water in this adherence. Methods: The left exorbital lacrimal gland was excised from eight female rats (body wt 187 + 6 [SD] g) under pentobarbital. Organ wt was 75 + 15 mg. A hair dryer emitting air at 100–104oC was used to heat the deep surface of each excised gland or its unoccupied bed before replacing the gland in its bed. After each use the rat was elevated and rotated so the gland faced downwardly. The organ was reweighed before being replaced. Heating was repeated until the organ fell from its bed. The last weighing was then done. The individual drying periods and gland weight changes were tabulated. Statistical analysis was by "t" test for paired comparisons or ANOVA for multiple ones. P < 0.05 indicated significance. Results: Heating caused progressive gland wt loss (F = 16.3). After 75 s of heating organ wt decreased to 66 + 10 mg. After 60 more s of heating it was 60 + 9 mg. Not until the organ bed was dried for two min did the first four glands fall. They weighed 59 + 6 mg. The four remaining adherent weighed 62 + 12 mg (P = n.s.). After one min more of heating plus 1–1.5 min of organ bed heating three of them weighing 52 + 5 mg fell. The remaining adherent gland was the largest, 71 mg. After an additional min of heating and two min of heating its organ bed it finally fell, weighing 64 mg. The range of heating for the entire study was from 2.25 min for the gland plus 2 min for the bed, total 4.25 min, to 4.25 min of organ drying plus 6 min for the bed, total 10.25 min. Heating caused loss of the normal sheen of both the organ capsule and its bed. Mean lacrimal gland wt at the endpoint was 57 + 6 mg, 76% of the initial 75 + 15 mg wt (P = 0.005), a 24% difference. Comparing that with the last mean wt prior to the endpoint, 62 + 7 mg, which was 17% less than their initial value, the threshold of water loss needed to overcome adhesion may be determined. Conclusions: The freed exorbital lacrimal gland no longer adheres to its bed when it loses 17–24% of its water content. To accomplish that requires drying both the gland and its bed. Their water comprises the interstitial fluid hydrating the glycosaminoglycans of the bed as well as the intraglandular fluid. Water is exchangeable between the two compartments because drying the gland alone was insufficient to loosen its adherence. This was because sufficient water emanated from the bed to coat the deep capsular surface. Adherence could only be prevented by drying the organ bed in addition to the gland so sufficient compartmental exchange of water could not take place.

Keywords: lacrimal gland • extracellular matrix 
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