Voltage-gated potassium channel Kv1.3 in rabbit ciliary epithelium regulates the membrane potential via coupling intracellular calcium.
BACKGROUND
The cell layer of the ciliary epithelium is responsible for aqueous humor secretion and maintenance. Ion channels play an important role in these processes. The main aim of this study was to determine whether the well-characterized members of the Kv1 family (Kv1.3) contribute to the Kv currents in ciliary epithelium.


METHODS
New Zealand White rabbits were maintained in a 12 hours light/dark cycle. Ciliary epithelium samples were isolated from the rabbits. We used Western blotting and immunocytochemistry to identify the expression and location of a voltage-gated potassium channel Kv1.3 in ciliary body epithelium. Membrane potential change after adding of Kv1.3 inhibitor margatoxin (MgTX) was observed with a fluorescence method.


RESULTS
Western blotting and immunocytochemical studies showed that the Kv1.3 protein expressed in pigment ciliary epithelium and nonpigment ciliary epithelium, however it seemed to express more in the apical membrane of the nonpigmented epithelial cells. One nmol/L margatoxin, a specific inhibitor of Kv1.3 channels caused depolarization of the cultured nonpigmented epithelium (NPE) membrane potential. The cytosolic calcium increased after NPE cell depolarization, this increase of cytosolic calcium was partially blocked by 12.5 micromol/L dantrolene and 10 micromol/L nifedipine. These observations suggest that Kv1.3 channels modulate ciliary epithelium potential and effect calcium dependent mechanisms.


CONCLUSIONS
Kv1.3 channels contribute to K+ efflux at the membrane of rabbit ciliary epithelium.
Li
Yan-feng
YF
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong 510060, China.
Zhuo
Ye-hong
YH
Bi
Wei-na
WN
Bai
Yu-jing
YJ
Li
Yan-na
YN
Wang
Zhi-jian
ZJ
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002924:Ciliary Body / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D051664:Kv1.3 Potassium Channel / Q000378:metabolism / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D011817:Rabbits
D051664:Kv1.3 Potassium Channel; D002118:Calcium