64 research outputs found
In vitro and in vivo delivery of the secretagogue diadenosine tetraphosphate from conventional and silicone hydrogel soft contact lenses
Purpose: To evaluate the possible use of soft contact lenses (CL) to improve the secretagogue
role of diadenosine tetraphosphate (Ap4A) promoting tear secretion.
Methods: Two conventional hydrogel CL (Omafilcon A and Ocufilcon D) and two silicone hydrogel
(SiH) CL (Comfilcon A and Balafilcon A) were used. Ap4A was loaded into the lenses by soaking
in a 1 mM Ap4A solution during 12 h. In vitro experiments were performed by placing the lenses
in multi-wells during 2 h containing 1 ml of ultrapure water. 100 l aliquots were taken at time
zero and every minute for the first 10 min, and then every 15 min. In vivo experiments were
performed in New Zealand rabbits and both the dinucleotide release from SiH and tear secretion
were measured by means of Schirmer strips and high-pressure liquid chromatography (HPLC)
analysis.
Results: Ap4A in vitro release experiments in hydrogel CL presented a release time 50 (RT50) of
3.9
±
0.2 min and 3.1
±
0.1 min for the non-ionic and the ionic CL, respectively. SiH CL released
also Ap4A with RT50 values of 5.1
±
0.1 min for the non-ionic and 2.7
±
0.1 min for the ionic CL.
In vivo experiments with SiH CL showed RT50 values of 9.3
±
0.2 min and 8.5
±
0.2 min for the
non-ionic and the ionic respectively. The non-ionic lens Ap4A release was able to induce tear
secretion above baseline tear levels for almost 360 min.
Conclusion: The delivery of Ap4A is slower and the effect lasts longer with non-ionic lenses than
ionic lenses.(undefined
Immunolocalisation of P2Y receptors in the rat eye
Nucleotides present an important role in ocular physiology which has been demonstrated by recent works that indicate their involvement in many ocular processes. P2Y are important among P2 receptors since they can control tear production, corneal wound healing, aqueous humour dynamics and retinal physiology. Commercial antibodies have allowed us to investigate the distribution of P2Y receptors in the cornea, anterior and posterior chamber of the eye and retina. The P2Y1 receptor was present mainly in cornea, ciliary processes, and trabecular meshwork. The P2Y2 receptors were present in cornea, ciliary processes and retinal pigmented epithelium. P2Y4 was present in cornea, ciliary processes, photoreceptors, outer plexiform layer and ganglion cell layer. The P2Y6 presented almost an identical distribution as the P2Y4 receptor. The P2Y11 was also detectable in the retinal pigmented epithelium. The detailed distribution of the receptors clearly supports the recent findings indicating the relevant role of nucleotides in the ocular function
Homologous and heterologous desensitization of histamine H1-and ATP-receptors in the smooth muscle cell line, DDT1MF-2: the role of protein kinase C
Differential effects of norepinephrine and phorbol ester on alpha-1 adrenergic receptor number and surface-accessibility in DDT1 MF-2 cells
Regulation of histamine H1 receptor-mediated phosphoinositide hydrolysis by histamine and phorbol esters in DDT1 MF-2 cells
Effects of Diquafosol Sodium Eye Drops on Tear Film Stability in Short BUT Type of Dry Eye
Effect of INS50589, a Reversible ADP-Receptor Antagonist, on Platelet Function and Blood Loss in a Canine Model of Cardiopulmonary Bypass.
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