Lacrimal fluid and electrolyte secretion: a review.
Lacrimal gland fluid is an important component of the precorneal tear film. The rate of lacrimal gland fluid secretion is controlled primarily by parasympathetic innervation, and it is, apparently, modulated by sympathetic innervation. Lacrimal gland fluid is produced in two stages, secretion of a primary fluid which resembles an isotonic ultrafiltrate of plasma in the acinus-early intercalated duct region, and secretion of a KCl-rich fluid in subsequent ductal elements. Little is known about the electrolyte transport mechanisms of the ductal epithelia. Recent work using a variety of techniques, including tracer flux measurements, intracellular electrical recording, intracellular ion activity measurements, patch clamping, and analytical subcellular fractionation, supports a model for transcellular Cl-secretion in the acinus which involves Cl--selective channels in the apical plasma membrane and an array of Na+/H+ antiporters, Cl-/HCO3-antiporters, K+ channels, and Na,K-ATPase in the basal-lateral plasma membrane.
Mircheff
A K
AK
Department of Physiology and Biophysics, University of Southern California, School of Medicine, Los Angeles 90033.
D000818:Animals; D017920:Antiporters; D001692:Biological Transport; D002352:Carrier Proteins; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism; D004573:Electrolytes / Q000378:metabolism*; D004847:Epithelial Cells; D006801:Humans; D007765:Lacrimal Apparatus / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism; D011817:Rabbits; D012965:Sodium Chloride / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000378:metabolism
D017920:Antiporters; D002352:Carrier Proteins; D018118:Chloride Channels; D002712:Chlorides; D004573:Electrolytes; D008565:Membrane Proteins; D015221:Potassium Channels; D012965:Sodium Chloride; D000254:Sodium-Potassium-Exchanging ATPase