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Na,K-ATPase polypeptide upregulation responses in lens epithelium.
Invest Ophthalmol Vis Sci. 1998 Apr; 39(5):763-8.IO

Abstract

PURPOSE

In a previous study, an increase in Na,K-ATPase alpha 2 expression was detected in the epithelium of porcine lenses exposed to amphotericin B, an ionophore that also increases lens sodium and stimulates active sodium transport. The purpose of the present study was to determine whether an increase of Na,K-ATPase alpha 2 synthesis is a response to an episode of rapid Na-K transport or whether the increase in lens sodium alone can initiate the response.

METHODS

Western blot analyses were conducted to probe for Na,K-ATPase alpha polypeptides in membrane material isolated from porcine lens epithelium. Ouabain-sensitive adenosine triphosphate hydrolysis was used as an index of Na,K-ATPase activity, and lens ion content was determined by atomic absorption spectrophotometry. 86-Rubidium (86Rb) uptake was measured as an indicator for active potassium transport.

RESULTS

86Rb uptake was markedly diminished in lenses exposed to dihydro-ouabain (DHO), signifying inhibition of active sodium-potassium transport. Consistent with this, the sodium content of DHO-treated lenses increased. By western blot analysis, a marked increase of Na,K-ATPase alpha 2 polypeptide could be detected in the epithelium of DHO-treated lenses. To rule out the possibility that apparent stimulation of Na,K-ATPase alpha 2 synthesis stemmed from binding of DHO to Na,K-ATPase sites, experiments were conducted to confirm an increase of Na,K-ATPase alpha 2 polypeptide in the epithelium of lenses exposed to low-potassium medium to inhibit active sodium-potassium transport. Consistent with the apparent increase of Na,K-ATPase polypeptide, Na,K-ATPase activity was detectably increased in epithelial material isolated from lenses pretreated with DHO or low-potassium medium.

CONCLUSIONS

An increase in Na,K-ATPase alpha 2 polypeptide can occur in the epithelium of lenses subjected to an episode of sodium pump inhibition. This suggests the response could be triggered by an increase in cell sodium and does not necessarily require a period of stimulated active sodium-potassium transport.

Authors+Show Affiliations

Department of Ophthalmology and Visual Sciences, University of Louisville, Kentucky, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9538883

Citation

Delamere, N A., et al. "Na,K-ATPase Polypeptide Upregulation Responses in Lens Epithelium." Investigative Ophthalmology & Visual Science, vol. 39, no. 5, 1998, pp. 763-8.
Delamere NA, Manning RE, Liu L, et al. Na,K-ATPase polypeptide upregulation responses in lens epithelium. Invest Ophthalmol Vis Sci. 1998;39(5):763-8.
Delamere, N. A., Manning, R. E., Liu, L., Moseley, A. E., & Dean, W. L. (1998). Na,K-ATPase polypeptide upregulation responses in lens epithelium. Investigative Ophthalmology & Visual Science, 39(5), 763-8.
Delamere NA, et al. Na,K-ATPase Polypeptide Upregulation Responses in Lens Epithelium. Invest Ophthalmol Vis Sci. 1998;39(5):763-8. PubMed PMID: 9538883.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Na,K-ATPase polypeptide upregulation responses in lens epithelium. AU - Delamere,N A, AU - Manning,R E,Jr AU - Liu,L, AU - Moseley,A E, AU - Dean,W L, PY - 1998/4/16/pubmed PY - 2001/3/28/medline PY - 1998/4/16/entrez SP - 763 EP - 8 JF - Investigative ophthalmology & visual science JO - Invest Ophthalmol Vis Sci VL - 39 IS - 5 N2 - PURPOSE: In a previous study, an increase in Na,K-ATPase alpha 2 expression was detected in the epithelium of porcine lenses exposed to amphotericin B, an ionophore that also increases lens sodium and stimulates active sodium transport. The purpose of the present study was to determine whether an increase of Na,K-ATPase alpha 2 synthesis is a response to an episode of rapid Na-K transport or whether the increase in lens sodium alone can initiate the response. METHODS: Western blot analyses were conducted to probe for Na,K-ATPase alpha polypeptides in membrane material isolated from porcine lens epithelium. Ouabain-sensitive adenosine triphosphate hydrolysis was used as an index of Na,K-ATPase activity, and lens ion content was determined by atomic absorption spectrophotometry. 86-Rubidium (86Rb) uptake was measured as an indicator for active potassium transport. RESULTS: 86Rb uptake was markedly diminished in lenses exposed to dihydro-ouabain (DHO), signifying inhibition of active sodium-potassium transport. Consistent with this, the sodium content of DHO-treated lenses increased. By western blot analysis, a marked increase of Na,K-ATPase alpha 2 polypeptide could be detected in the epithelium of DHO-treated lenses. To rule out the possibility that apparent stimulation of Na,K-ATPase alpha 2 synthesis stemmed from binding of DHO to Na,K-ATPase sites, experiments were conducted to confirm an increase of Na,K-ATPase alpha 2 polypeptide in the epithelium of lenses exposed to low-potassium medium to inhibit active sodium-potassium transport. Consistent with the apparent increase of Na,K-ATPase polypeptide, Na,K-ATPase activity was detectably increased in epithelial material isolated from lenses pretreated with DHO or low-potassium medium. CONCLUSIONS: An increase in Na,K-ATPase alpha 2 polypeptide can occur in the epithelium of lenses subjected to an episode of sodium pump inhibition. This suggests the response could be triggered by an increase in cell sodium and does not necessarily require a period of stimulated active sodium-potassium transport. SN - 0146-0404 UR - https://www.unboundmedicine.com/medline/citation/9538883/NaK_ATPase_polypeptide_upregulation_responses_in_lens_epithelium_ L2 - https://iovs.arvojournals.org/article.aspx?volume=39&issue=5&page=763 DB - PRIME DP - Unbound Medicine ER -