Regulation of ocular mucin secretion by P2Y2 nucleotide receptors in rabbit and human conjunctiva

• Published in: Experimental eye research Vol. 67; no. 3; pp. 341 - 346
• Main Authors: JUMBLATT, J. E, JUMBLATT, M. M
• Format: Journal Article
• Language: English
• Published: London Elsevier 01-09-1998
• Subjects: Adenosine Diphosphate - pharmacology; Adenosine Monophosphate - pharmacology; Adenosine Triphosphate - analogs & derivatives; Adenosine Triphosphate - pharmacology; Aged; Aged, 80 and over; Animals; Biological and medical sciences; Conjunctiva - cytology; Conjunctiva - drug effects; Conjunctiva - metabolism; Electrophoresis, Polyacrylamide Gel; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Goblet Cells - drug effects; Goblet Cells - secretion; Humans; Immunoblotting; Inositol 1,4,5-Trisphosphate - pharmacology; Middle Aged; Mucins - secretion; Rabbits; Receptors, Purinergic P2 - metabolism; Receptors, Purinergic P2Y2; Stimulation, Chemical; Thionucleotides - pharmacology; Uridine Triphosphate - pharmacology; Vertebrates: nervous system and sense organs; Human; Purine nucleotide; Secretion; Rabbit; P2 Purinergic receptor; Lagomorpha; Conjunctiva; Eye; Visual system; Vertebrata; Mammalia; Mucin; Pyrimidine nucleotide
• ISSN: 0014-4835; 1096-0007
• DOI: 10.1006/exer.1998.0520

The effects of adenine analogues on secretion of high molecular weight, mucin-like glycoproteins (mucins) by conjunctival goblet cells were investigated using isolated rabbit and human conjunctiva. Mucin secretion was assayed using a quantitative dot-blot assay of Helix pomatia agglutinin-horseradish peroxidase binding to mucins absorbed to nitrocellulose filters. In rabbit conjunctiva, exogenous ATP (10(-7)-10(-3) m) induced a concentration-dependent, four-fold increase in mucin secretion that reached a plateau 15 min after drug addition. The rank order of potency of agonists was UTP>=ATPgammaS>ATP>ITP>ADP>>AMP. Adenosine, alpha,beta-methylene- ATP and beta,gamma-methylene-ATP were ineffective in stimulating mucin release. The response to ATP was unmodified by the putative P2 purinergic antagonists suramin or reactive blue (5x10(-5) m). In human conjunctiva, ATP and UTP were nearly equipotent in stimulating mucin secretion with an EC50 congruent with5x10(-6) m. These findings demonstrate that rabbit and human conjunctival cells contain functional P2Y2 (formerly designated as P2U) nucleotide receptors that govern mucin secretion. These receptors may provide useful pharmacological targets for therapeutic modulation of tear film mucins in dry-eye disorders and/or corneal wound healing.