Fluid secreted by the lacrimal gland is an essential component of tears and is estimated to contribute approximately 50% of the liquid volume bathing the cornea (Walcott, 1998). Recently in situ measurements of fluid production from the lacrimal glands of mice have demonstrated stimulated flow rates of 0.2-0.6 uL/minute (Walcott et al., 2002; Paranyuk et al., 2001; Moore et al, 2000). Our preliminary data indicates that the NKCC1 Na+, K+, 2CI- co-transporter and Bkca channels play important roles in fluid production of the lacrimal gland. We propose the use of knockout mice along with NZB mice (compromised fluid flow, Paranyuk et al., 2001) to study their respective roles in fluid production by the lacrimal gland. Further we propose the use of activators and inhibitors of PKC to delineate its role in the regulation of the NKCC1 co-transporter and Bkca channel. Both systems have been shown to be influenced/moduate/regulate by PKC (Standen and Quayle, 1998;Zhou et al., 2001; Clerice etal., 1995). Our proposal is focused on addressing the following hypotheses:
Aim 1 Hypothesis: Basolateral blockade of the salt co-transporter (NKCC1) will significantly reduce stimulated fluid flow in controls but will be similar to NKCC1 knockout flow rates. We will also compare and contrast control and knockouts with NZB. We propose the use of NZB because our preliminary results indicates that the NZB acinar cells have significantly less amounts of NKCC1 than controls.
Aim 2 : Hypothesis: Apical membrane BKca channels contribute to normal fluid production of the lacrimal gland. We will test control (C57) and Bkca Beta 1 knockout mice.
Aim 3 : Hypothesis: PKC activity affects fluid production via regulation of K channels and/or NKCC1 transporters. We will test controls, NZB and the two knockouts (Beta1 and NKCC1).
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